Fix multiarch package upgrade issue

When checking for negative dependencies in MarkInstall() ensure that
only dependencies that are relevant (i.e. getting installed) are
checked.

apt-pkg/depcache.cc

@@ -1253,6 +1253,11 @@ bool pkgDepCache::MarkInstall(PkgIterator const &Pkg,bool AutoInst,
 	    if (PkgState[Pkg->ID].InstallVer == 0)
 	       continue;
 
+            /* Ignore negative dependencies that we are not going to 
+               get installed */
+            if (PkgState[Pkg->ID].InstallVer != *I)
+               continue;
+
 	    if ((Start->Version != 0 || TrgPkg != Pkg) &&
 		PkgState[Pkg->ID].CandidateVer != PkgState[Pkg->ID].InstallVer &&
 		PkgState[Pkg->ID].CandidateVer != *I &&

test/integration/test-bug-multiarch-upgrade

@@ -0,0 +1,29 @@
+#!/bin/sh
+set -e
+
+TESTDIR=$(readlink -f $(dirname $0))
+. $TESTDIR/framework
+setupenvironment
+configarchitecture 'amd64' 'i386'
+
+insertinstalledpackage 'libcups2' 'amd64' '1' 'Multi-Arch: same'
+insertinstalledpackage 'libcups2' 'i386' '1' 'Multi-Arch: same'
+
+insertpackage 'unstable' 'libcups2' 'amd64' '0' 'Multi-Arch: same'
+insertpackage 'unstable' 'libcups2' 'amd64' '2' 'Multi-Arch: same'
+insertpackage 'unstable' 'libcups2' 'i386' '0' 'Multi-Arch: same'
+insertpackage 'unstable' 'libcups2' 'i386' '2' 'Multi-Arch: same'
+
+setupaptarchive
+
+testequal 'Reading package lists...
+Building dependency tree...
+The following extra packages will be installed:
+  libcups2
+The following packages will be upgraded:
+  libcups2 libcups2:i386
+2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
+Inst libcups2 [1] (2 unstable [amd64]) [libcups2:amd64 on libcups2:i386] [libcups2:i386 on libcups2:amd64] [libcups2:i386 ]
+Inst libcups2:i386 [1] (2 unstable [i386])
+Conf libcups2 (2 unstable [amd64])
+Conf libcups2:i386 (2 unstable [i386])' aptget install -s libcups2:i386