Merge lp:~mterry/launchpad-buildd/prefer-install into lp:launchpad-buildd

[Michael Terry]

This is an attempt to fix bug 1030893, which is causing some bogus dep-waits.

From looking at the sbuild fork code, what happens is that libsocket-perl gets marked as installable and perl gets marked as upgradeable. But the code prefers to upgrade over install, so it tries to upgrade the existing perl instead.

I'm curious in what situations would an upgrade be useful? Any package in the chroot should already be the latest version, since the first part of the build upgrades the packages in the chroot.

So with that logic in mind, this branch prefers installing new packages over upgrading existing ones.

[Richard Harding (rharding)]

This makes sense to me, but it seems like there would have been a reason for setting it up this way originally. So I'm going to ok, but ask William (lucky since he's got the most commits recently against launchpad-buildd) to give an ok as well.

review: Approve

[Michael Terry (mterry)]

poke

[Michael Terry (mterry)]

William suggested Adam Conrad should be the one to review it, so punting this to him.

[Adam Conrad (adconrad)]

I have to follow the logic through and do some testing, but a naive glance at this would suggest this might just trade one set of incorrect behaviours for another (like, say, installing lib-foo-perl even if perl is a high enough version to satisfy an | dep).

[Michael Terry (mterry)]

I *believe* if that happened, we don't go into this branch of code. That is, this code is only reached if we can't satisfy the or-dependency at all with installed software.

And all packages should be at their latest archive versions by this point (we early do an apt-get upgrade I believe), so any packages marked as upgradeable should never actually be able to be upgraded were we to try it.

[Colin Watson (cjwatson)]

We now use a backport of the stock sbuild from Ubuntu which lets apt-get do the hard work here and doesn't suffer from this problem, so there's no more need for this change.

review: Disapprove

Unmerged revisions

55. By Michael Terry on 2012-07-30

prefer installing new packages to upgrading existing chroot packages

=== modified file 'sbuild'
--- sbuild	2012-03-22 10:07:59 +0000
+++ sbuild	2012-07-30 18:37:20 +0000
@@ -2078,14 +2078,14 @@
 			}
 		}
 		if (!$is_satisfied) {
-			if ($upgradeable) {
+			if ($installable) {
+				print "using $installable for install\n" if $main::debug;
+				push( @$pos_list, $installable );
+			}
+			elsif ($upgradeable) {
 				print "using $upgradeable for upgrade\n" if $main::debug;
 				push( @$pos_list, $upgradeable );
 			}
-			elsif ($installable) {
-				print "using $installable for install\n" if $main::debug;
-				push( @$pos_list, $installable );
-			}
 			elsif ($downgradeable) {
 				print PLOG "To satisfy this dependency the package(s) would ",
 						   "have\n",