Bug#922737: lintian rarely hangs

[Helmut Grohne <helmut@subdivi.de>]

Package: lintian
Version: 2.6.0
Severity: important
User: helmutg@debian.org
Usertags: rebootstrap

I use lintian to detect wrongly cross built packages. In this setup,
lintian is run by sbuild inside the (unstable) schroot after the build.
I pass "-T
binary-from-other-architecture,triplet-dir-and-architecture-mismatch" to
lintian and it all works fine ... most of the time.

In roughly 1/2000 builds, lintian hangs. Now the bad part is that I have
little details on what is going on here.

 * A process list shows just "lintian" without any command line flags.
 * lintian has a zombie chiled called "[rm]".
 * lintian has the following file descriptors:
   + 0 is /dev/null inherited from the sbuild invocation
   + 1 and 2 are the same writable pipe (presumably to sbuild)
   + 3 is /dev/null (inside the schroot) for writing
   + 4 and 5 are the read and write ends of a pipe
   + 6 is /usr/share/perl5/Net/DNS/Resolver/Base.pm inside the schroot
 * It already happend with 2.6.0 and continues to happen with 2.7.0.
 * Attaching the hanging lintian with strace only yields
   restart_syscall.

Given the 1/2000 builds nature, it takes a while (days) to reproduce.
I'll leave one such hanging process around for a while in case you have
ideas on how to debug this.

Helmut