yum exitcode changes in 3.2.19-3.fc9 break some mock builds

[Paul Howarth]

Today I tried building (in mock on a Fedora 9 host) some nmap packages 
for CentOS3 as version 4.76 came out. The mock build crashed out at the 
setup stage, due to the %pre script for the "dev" package failing (it 
thinks devfs is mounted). As I had built packages for version 4.75 only 
a couple of days ago, I tried rebuilding that and it now failed in the 
same way. I'd installed a bunch of updates in the last couple of days 
but the only one I could think of that might have caused that was the 
yum upgrade. So I downgraded yum from 3.2.19-3.fc9 to 3.2.17-2.fc9 and 
tried the build again, and this time it worked.

The salient difference in the root.log was this:

  DEBUG util.py:250:  Cannot install the dev package: mounted devfs 
detected.
+DEBUG util.py:250: 
--------------------------------------------------------------------------------
+DEBUG util.py:250:  Total                                           1.5 
GB/s |  14 MB     00:00
  DEBUG util.py:250:  error: %pre(dev-3.3.12.3-1.centos.0.x86_64) 
scriptlet failed, exit status 1
  DEBUG util.py:250:  error:   install: %pre scriptlet failed (2), 
skipping dev-3.3.12.3-1.centos.0
  DEBUG util.py:250:  ls:
@@ -233,8 +236,7 @@
  DEBUG util.py:250:  mkinitrd failed
  DEBUG util.py:250:  Installed: libpcap.x86_64 14:0.7.2-7.E3.5 
openssl-devel.x86_64 0:0.9.7a-33.24 pcre-devel.x86_64 0:3.9-10.4 
pkgconfig.x86_64 1:0.14.0-5 zlib-devel.x86_64 0:1.1.4-10.EL3
  DEBUG util.py:250:  Dependency Installed: dev.x86_64 
0:3.3.12.3-1.centos.0 kernel.x86_64 0:2.4.21-57.EL krb5-devel.x86_64 
0:1.2.7-68 losetup.x86_64 0:2.11y-31.24 lvm.x86_64 0:1.0.8-14 
mkinitrd.x86_64 0:3.5.13.6-1
-DEBUG util.py:311:  Child returncode was: 0
-DEBUG backend.py:436:  Copying packages to result dir
+DEBUG util.py:311:  Child returncode was: 1
  DEBUG backend.py:484:  umount -n /var/lib/mock/centos-3-x86_64/root/proc
  DEBUG util.py:272:  Executing command: umount -n 
/var/lib/mock/centos-3-x86_64/root/proc
  DEBUG util.py:311:  Child returncode was: 0


So the scriptlet failures that didn't formerly affect affect mock builds 
due to the zero exit code of yum are now causing build failures due to a 
"1" exit code.

I'm not sure what the best approach to fixing this should be. It makes 
perfect sense to me for yum to return a non-zero exit code when there's 
a scriptlet failure yet in some cases this is a problem that doesn't 
affect the subsequent build.

As I suspect that this is a problem that mainly affects legacy 
distribution versions, perhaps there could be a mock option that could 
be set in the config file to ignore the yum exit code?

Paul.