Ubuntu-bug: a quilt problem while making qemu-2.6.1 or qemu 2.7.0 deb package

1. I use Ubuntu 16.10 beta(daily updated to the latest state) and ms Windows 10 on a virtual machine of qemu.
Some patches didn't apply correcly or skipped without errror while making qemu-2.6.1 or qemu-2.7.0 by coping and modifying 'debian' directory of Ubuntu qemu-2.6.0 source package.(qemu-2.6.0 source package itself didn't show such problem)

2. I changed version in debian/changelog and performed 'dpkg-buildpackage -rfakeroot -b -us -uc'.
Some patches became obsolete due to upstream patch and I commented out them from 'debian/patches/series' file.
But since some patches were incorrecly applied or skipped without warnings or error messages, the compile process failed.
I found no-pie.patch is incorrectly applied and this causes compile failure, and define-ubuntu-machine-types.patch was skipped entirely without any warings or error messages.
After I regenerated no-pie.patch the compile process went well, but after installing packages and executing libvirtd and virtlogd service. I encountered error related to machine name.
Though this problem was solved by modifying machine name from pc-i440fx-utopy to pc-i440fx-2.7 accroding to the convention of qemu itself in /etc/libvirt/qemu/win10.xml and restaring libvirtd and virtlogd service as follows:

# regenerated no-pie.patch

--- a/rules.mak.orig 2016-09-03 00:34:23.000000000 +0900
+++ b/rules.mak 2016-09-03 21:04:23.661962561 +0900
@@ -92,7 +92,12 @@
        $(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@), " CP $(subst /,-,$@)"))

-LD_REL := $(CC) -nostdlib -Wl,-r $(LD_REL_FLAGS)
+ifeq (,$(shell $(CC) -fsyntax-only -no-pie -xc /dev/null 2>&1))
+no_pie:=-no-pie
+else
+no_pie:=
+endif
+LD_REL := $(CC) $(no_pie) -nostdlib -Wl,-r $(LD_REL_FLAGS)

 %.mo:
        $(call quiet-command,$(LD_REL) -o $@ $^," LD -r $(TARGET_DIR)$@")
...

# /etc/libvirt/qemu/win10.xml

...
<os>
    <type arch='x86_64' machine='pc-i440fx-2.7'>hvm</type>
    <bootmenu enable='no'/>
  </os>
...

$ sudo service libvirtd restart && sudo service virtlogd restart &

$ virt-manager

3. BTW, if I manually apply only define-ubuntu-machine-types.patch, three is no problem.

$ patch -p1 -E --dry-run < debian/patches/ubuntu/define*
checking file hw/i386/pc_piix.c
Hunk #1 succeeded at 442 with fuzz 1 (offset 22 lines).
Hunk #2 succeeded at 1094 (offset 34 lines).

I think the right behaviour is that if a patch is not applied correctly the quilt system should emit error messages and dpkg-buildpackage shoud stop the build process.

4. Moreover, even if I perform 'fakeroot debian/rules clean', the .pc directory remains instead of being removed.