I'm using Ubuntu 15.04 dev with sysvinit-utils 2.88dsf-53.2ubuntu1 and for a few days I'm seeing always on booting error messages like from this booting instance:
sworddragon@ubuntu:~$ dmesg | grep startpar-bridge
[ 11.251848] init: startpar-bridge (hwclock.sh--started) main process (273) terminated with status 127
[ 11.252052] init: startpar-bridge (plymouth-ready-startup-started) main process (275) terminated with status 127
[ 11.261156] init: startpar-bridge (hwclock--started) main process (276) terminated with status 127
[ 11.264019] init: startpar-bridge (hostname--stopped) main process (279) terminated with status 127
[ 11.264298] init: startpar-bridge (hwclock--stopped) main process (280) terminated with status 127
[ 11.264497] init: startpar-bridge (hostname.sh--started) main process (281) terminated with status 127
[ 11.300143] init: startpar-bridge (plymouth-upstart-bridge--started) main process (282) terminated with status 127
[ 11.441524] init: startpar-bridge (plymouth--started) main process (285) terminated with status 127
[ 11.458996] init: startpar-bridge (plymouth-upstart-bridge--stopped) main process (286) terminated with status 127
[ 11.459185] init: startpar-bridge (plymouth--stopped) main process (287) terminated with status 127
[ 11.533663] init: startpar-bridge (plymouth-ready-startup-stopped) main process (290) terminated with status 127
[ 11.979125] init: startpar-bridge (mountall--started) main process (293) terminated with status 127
[ 11.982885] init: startpar-bridge (mounted-proc--started) main process (301) terminated with status 127
[ 11.983119] init: startpar-bridge (init.d/cpufreq--started) main process (302) terminated with status 127
[ 11.983318] init: startpar-bridge (mounted-dev--started) main process (303) terminated with status 127
[ 11.983509] init: startpar-bridge (mounted-run--started) main process (304) terminated with status 127
[ 12.061686] init: startpar-bridge (mounted-proc--stopped) main process (314) terminated with status 127
[ 12.062344] init: startpar-bridge (mounted-dev--stopped) main process (315) terminated with status 127
[ 12.210948] init: startpar-bridge (mounted-run--stopped) main process (320) terminated with status 127
[ 12.369938] init: startpar-bridge (mounted-debugfs--started) main process (332) terminated with status 127
[ 12.370143] init: startpar-bridge (mounted-debugfs--stopped) main process (334) terminated with status 127
[ 12.981052] init: startpar-bridge (container-detect--stopped) main process (344) terminated with status 127
[ 13.681176] init: startpar-bridge (checkroot.sh--started) main process (354) terminated with status 127
[ 13.681397] init: startpar-bridge (checkfs.sh--started) main process (355) terminated with status 127
[ 13.681599] init: startpar-bridge (checkroot-bootclean.sh--started) main process (356) terminated with status 127
[ 14.054084] init: startpar-bridge (init.d/automount--started) main process (357) terminated with status 127
[ 14.054297] init: startpar-bridge (init.d/log--started) main process (358) terminated with status 127
[ 16.168987] init: startpar-bridge (init.d/log--stopped) main process (391) terminated with status 127
[ 16.372769] init: startpar-bridge (resolvconf--started) main process (398) terminated with status 127
[ 17.038956] init: startpar-bridge (mountnfs-bootclean.sh--started) main process (409) terminated with status 127
[ 17.039189] init: startpar-bridge (mountkernfs.sh--started) main process (410) terminated with status 127
[ 17.039380] init: startpar-bridge (bootmisc.sh--started) main process (411) terminated with status 127
[ 17.039566] init: startpar-bridge (mountdevsubfs.sh--started) main process (412) terminated with status 127
[ 17.039757] init: startpar-bridge (mtab.sh--started) main process (413) terminated with status 127
[ 17.247406] init: startpar-bridge (mountall-bootclean.sh--started) main process (414) terminated with status 127
[ 17.530744] init: startpar-bridge (procps-instance-virtual-filesystems-started) main process (421) terminated with status 127
[ 17.530852] init: startpar-bridge (procps--started) main process (422) terminated with status 127
[ 17.748589] init: startpar-bridge (console-setup--started) main process (424) terminated with status 127
[ 17.748674] init: startpar-bridge (upstart-udev-bridge--started) main process (425) terminated with status 127
[ 17.748751] init: startpar-bridge (procps-instance-virtual-filesystems-stopped) main process (426) terminated with status 127
[ 17.769513] init: startpar-bridge (mountnfs.sh--started) main process (427) terminated with status 127
[ 17.792534] init: startpar-bridge (console-setup--stopped) main process (454) terminated with status 127
[ 17.886743] init: startpar-bridge (mounted-tmp--started) main process (456) terminated with status 127
[ 17.953992] init: startpar-bridge (init.d/cpufreq--stopped) main process (457) terminated with status 127
[ 18.181856] init: startpar-bridge (udev--started) main process (461) terminated with status 127
[ 18.393912] init: startpar-bridge (kmod--started) main process (470) terminated with status 127
[ 18.394440] init: startpar-bridge (udevmonitor--started) main process (474) terminated with status 127
[ 18.511757] init: startpar-bridge (mounted-tmp--stopped) main process (481) terminated with status 127
[ 18.512070] init: startpar-bridge (mountall.sh--started) main process (483) terminated with status 127
[ 18.566637] init: startpar-bridge (passwd--started) main process (490) terminated with status 127
[ 18.570979] init: startpar-bridge (passwd--stopped) main process (491) terminated with status 127
[ 18.592859] init: startpar-bridge (plymouth-log--started) main process (493) terminated with status 127
[ 18.615463] init: startpar-bridge (flush-early-job-log--started) main process (494) terminated with status 127
[ 19.342831] init: startpar-bridge (plymouth-log--stopped) main process (495) terminated with status 127
[ 19.439965] init: startpar-bridge (init.d/automount--stopped) main process (498) terminated with status 127
[ 19.440314] init: startpar-bridge (flush-early-job-log--stopped) main process (499) terminated with status 127
[ 19.487540] init: startpar-bridge (upstart-file-bridge--started) main process (502) terminated with status 127
[ 20.465543] init: startpar-bridge (dbus--started) main process (506) terminated with status 127
[ 20.589768] init: startpar-bridge (binfmt-support--started) main process (507) terminated with status 127
[ 20.909116] init: startpar-bridge (kmod--stopped) main process (531) terminated with status 127
[ 22.026972] init: startpar-bridge (network-interface-security-network-interface/lo-started) main process (589) terminated with status 127
[ 22.246645] init: startpar-bridge (network-interface-security-network-interface/eth0-started) main process (644) terminated with status 127
[ 22.839744] init: startpar-bridge (mountall-net--started) main process (688) terminated with status 127
[ 22.840211] init: startpar-bridge (init.d/update_connection--started) main process (689) terminated with status 127
[ 23.335556] init: startpar-bridge (mountall-net--stopped) main process (717) terminated with status 127
[ 23.540209] init: startpar-bridge (failsafe--started) main process (765) terminated with status 127
[ 23.562415] init: startpar-bridge (upstart-socket-bridge--started) main process (773) terminated with status 127
[ 23.811521] init: startpar-bridge (mountall-net--started) main process (813) terminated with status 127
[ 24.287377] init: startpar-bridge (procps-instance-static-network-up-started) main process (837) terminated with status 127
[ 24.287719] init: startpar-bridge (network-interface-eth0-started) main process (838) terminated with status 127
[ 24.287995] init: startpar-bridge (failsafe--stopped) main process (839) terminated with status 127
[ 24.288304] init: startpar-bridge (procps-instance-static-network-up-stopped) main process (840) terminated with status 127
[ 24.522972] init: startpar-bridge (rc-sysinit--started) main process (845) terminated with status 127
[ 24.538329] init: startpar-bridge (network-interface-lo-started) main process (851) terminated with status 127
[ 24.622136] init: startpar-bridge (mountall-net--stopped) main process (855) terminated with status 127
[ 25.845181] init: startpar-bridge (udevtrigger--stopped) main process (1006) terminated with status 127
[ 25.851467] init: startpar-bridge (udev-fallback-graphics--started) main process (1011) terminated with status 127
[ 25.851650] init: startpar-bridge (udevmonitor--stopped) main process (1012) terminated with status 127
[ 25.856454] init: startpar-bridge (network-interface-security-networking-started) main process (1017) terminated with status 127
[ 25.862145] init: startpar-bridge (udev-fallback-graphics--stopped) main process (1021) terminated with status 127
[ 25.866110] init: startpar-bridge (console-font--started) main process (1030) terminated with status 127
[ 25.994765] init: startpar-bridge (console-font--stopped) main process (1047) terminated with status 127
[ 26.041442] init: startpar-bridge (udev-finish--started) main process (1073) terminated with status 127
[ 26.041680] init: startpar-bridge (plymouth-splash--stopped) main process (1074) terminated with status 127
[ 26.095842] init: startpar-bridge (networking--started) main process (1075) terminated with status 127
[ 26.746859] init: startpar-bridge (init.d/update_time--started) main process (1145) terminated with status 127
[ 27.008652] init: startpar-bridge (cryptdisks--started) main process (1155) terminated with status 127
[ 27.080957] init: startpar-bridge (init.d/update_time--stopped) main process (1165) terminated with status 127
[ 27.081189] init: startpar-bridge (mountall--stopped) main process (1166) terminated with status 127
[ 27.278187] init: startpar-bridge (rc--started) main process (1209) terminated with status 127
[ 27.278646] init: startpar-bridge (rc-sysinit--stopped) main process (1210) terminated with status 127
[ 27.410115] init: startpar-bridge (plymouth-stop--started) main process (1220) terminated with status 127
[ 27.410298] init: startpar-bridge (alsa-restore--stopped) main process (1222) terminated with status 127
[ 27.519292] init: startpar-bridge (lxdm--started) main process (1224) terminated with status 127
[ 27.520055] init: startpar-bridge (irqbalance--started) main process (1226) terminated with status 127
[ 27.521117] init: startpar-bridge (cron--started) main process (1227) terminated with status 127
[ 27.542551] init: startpar-bridge (alsa-state--stopped) main process (1231) terminated with status 127
[ 31.041923] init: startpar-bridge (rc--stopped) main process (1382) terminated with status 127
[ 31.226178] init: startpar-bridge (tty1--started) main process (1385) terminated with status 127
[ 31.238020] init: startpar-bridge (setvtrgb--stopped) main process (1388) terminated with status 127
[ 32.476245] init: startpar-bridge (init.d/maintenance--started) main process (1393) terminated with status 127
[ 32.628323] init: startpar-bridge (init.d/maintenance--stopped) main process (1394) terminated with status 127
[ 32.669039] init: startpar-bridge (init.d/backup--started) main process (1396) terminated with status 127
[ 32.669628] init: startpar-bridge (init.d/update_connection--stopped) main process (1397) terminated with status 127
[ 32.844434] init: startpar-bridge (init.d/backup--stopped) main process (1398) terminated with status 127
I have noticed that /var/log/upstart contains many logs for these entries and they all seem to contain "/bin/sh: 1: exec: startpar-