* apt-pkg/depcache.cc:

  - don't install previously not installed providers in a try
    to statisfy a "Breaks: provides" dependency by upgrade

apt-pkg/depcache.cc

@@ -1444,8 +1444,11 @@ void pkgDepCache::MarkInstall(PkgIterator const &Pkg,bool AutoInst,
 	    VerIterator Ver(*this,*I);
 	    PkgIterator Pkg = Ver.ParentPkg();
 
-	    
-	       
+	    /* The List includes all packages providing this dependency,
+	       even providers which are not installed, so skip them. */
+	    if (PkgState[Pkg->ID].InstallVer == 0)
+	       continue;
+
 	    if (PkgState[Pkg->ID].CandidateVer != *I &&
 	        Start->Type == Dep::DpkgBreaks)
 	       MarkInstall(Pkg,true,Depth + 1, false, ForceImportantDeps);

debian/changelog

@@ -14,8 +14,11 @@ apt (0.8.9) UNRELEASED; urgency=low
   * apt-pkg/algorithms.cc:
     - if the package was explicitly marked as ToRemove don't
       consider it as a candidate for FixByInstall
+  * apt-pkg/depcache.cc:
+    - don't install previously not installed providers in a try
+      to statisfy a "Breaks: provides" dependency by upgrade
 
- -- David Kalnischkies <kalnischkies@gmail.com>  Wed, 10 Nov 2010 12:23:29 +0100
+ -- David Kalnischkies <kalnischkies@gmail.com>  Wed, 10 Nov 2010 13:22:39 +0100
 
 apt (0.8.8) unstable; urgency=low
 

test/integration/Packages-xorg-break-providers

@@ -0,0 +1,52 @@
+Package: xserver-xorg-video-intel
+Priority: optional
+Section: x11
+Installed-Size: 1292
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Version: 2:2.13.901-2
+Provides: xserver-xorg-video-8
+Filename: pool/main/x/xserver-xorg-video-intel/xserver-xorg-video-intel_2.13.901-2_i386.deb
+Size: 586964
+MD5sum: 72527f4b2c9d734e53202736e3177865
+Description: X.Org X server -- Intel i8xx, i9xx display driver
+
+Package: xserver-xorg-video-vesa
+Priority: optional
+Section: x11
+Installed-Size: 104
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Version: 1:2.3.0-4
+Provides: xserver-xorg-video-8
+Filename: pool/main/x/xserver-xorg-video-vesa/xserver-xorg-video-vesa_2.3.0-4_i386.deb
+Size: 27158
+MD5sum: 77bf2935c40b3b7739d431930e53d185
+Description: X.Org X server -- VESA display driver
+
+Package: xserver-xorg-video-vesa
+Priority: optional
+Section: x11
+Installed-Size: 104
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Version: 1:2.3.0-3
+Provides: xserver-xorg-video-6
+Filename: pool/main/x/xserver-xorg-video-vesa/xserver-xorg-video-vesa_2.3.0-3_i386.deb
+Size: 27122
+MD5sum: 0cd97be927c7d75f2a7230739f8f866c
+Description: X.Org X server -- VESA display driver
+
+Package: xserver-xorg-core
+Priority: optional
+Section: x11
+Installed-Size: 4436
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Source: xorg-server
+Version: 2:1.7.7-8
+Breaks: xserver-xorg-video-6
+Filename: pool/main/x/xorg-server/xserver-xorg-core_1.7.7-8_i386.deb
+Size: 2405050
+MD5sum: 976ddb13473e52903dd839d1f7ec390b
+Description: Xorg X server - core server

test/integration/status-xorg-break-providers

@@ -0,0 +1,22 @@
+Package: xserver-xorg-core
+Status: install ok installed
+Priority: optional
+Section: x11
+Installed-Size: 4436
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Source: xorg-server
+Version: 2:1.7.7-8
+Breaks: xserver-xorg-video-5
+Description: Xorg X server - core server
+
+Package: xserver-xorg-video-intel
+Status: install ok installed
+Priority: optional
+Section: x11
+Installed-Size: 1268
+Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
+Architecture: i386
+Version: 2:2.13.0-2
+Provides: xserver-xorg-video-6
+Description: X.Org X server -- Intel i8xx, i9xx display driver

test/integration/test-xorg-break-providers

@@ -0,0 +1,43 @@
+#!/bin/sh
+set -e
+
+TESTDIR=$(readlink -f $(dirname $0))
+. $TESTDIR/framework
+setupenvironment
+configarchitecture "i386"
+setupaptarchive
+
+# the new xserver-xorg-core breaks xserver-xorg-video-6
+# which both -intel (installed) and -vesa (not installed)
+# provided in their old version.
+# The test ensures that only -intel will be upgraded
+# (together with -core of course) and -vesa not touched.
+
+testequal 'Reading package lists...
+Building dependency tree...
+The following extra packages will be installed:
+  xserver-xorg-video-intel
+The following packages will be upgraded:
+  xserver-xorg-core xserver-xorg-video-intel
+2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
+Need to get 0 B/2992 kB of archives.
+After this operation, 24.6 kB of additional disk space will be used.
+E: Trivial Only specified but this is not a trivial operation.' aptget install xserver-xorg-core --trivial-only
+
+testequal 'Reading package lists...
+Building dependency tree...
+The following packages will be upgraded:
+  xserver-xorg-core xserver-xorg-video-intel
+2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
+Need to get 0 B/2992 kB of archives.
+After this operation, 24.6 kB of additional disk space will be used.
+E: Trivial Only specified but this is not a trivial operation.' aptget upgrade --trivial-only
+
+testequal 'Reading package lists...
+Building dependency tree...
+The following packages will be upgraded:
+  xserver-xorg-core xserver-xorg-video-intel
+2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
+Need to get 0 B/2992 kB of archives.
+After this operation, 24.6 kB of additional disk space will be used.
+E: Trivial Only specified but this is not a trivial operation.' aptget dist-upgrade --trivial-only