xulrunner debug symbols are not usable

Binary package hint: xulrunner-1.9.1

1)
$ lsb_release -rd
Description: Ubuntu 9.10
Release: 9.10
2)
$ apt-cache policy xulrunner-1.9.1-dbg
xulrunner-1.9.1-dbg:
  Installed: 1.9.1.7+nobinonly-0ubuntu1
  Candidate: 1.9.1.7+nobinonly-0ubuntu1
  Version table:
     1.9.1.8~hg20091231r26707+nobinonly-0ubuntu1~umd1~karmic 0
         50 http://ppa.launchpad.net karmic/main Packages
     1.9.1.6+nobinonly-0ubuntu1 0
        300 http://ru.archive.ubuntu.com lucid/main Packages
 *** 1.9.1.6+nobinonly-0ubuntu0.9.10.1 0
        600 http://ru.archive.ubuntu.com karmic-updates/main Packages
        600 http://security.ubuntu.com karmic-security/main Packages
        100 /var/lib/dpkg/status
     1.9.1.3+build1+nobinonly-0ubuntu6 0
        600 http://ru.archive.ubuntu.com karmic/main Packages

Steps to reproduce:
$ gdb firefox
(gdb) b nsSHistory::GoBack()
(gdb) r
(gdb) l

3) Expected result:
Source code is printed at breakpoint

4) Actual result:
gdb complains it cannot find source code.

This happens because xulrunner is built "in tree". Whenever gdb is pointed to for source, it tries to find the files in present working directory.

The solution is to use VPATH build (recommended upstream). Package system patch is attached.