* Treat the Important flag like the Essential flag with two differences:

  - No Immediate configuration (see above)
  - Not automatically installed during dist-upgrade

apt-pkg/algorithms.cc

@@ -556,7 +556,8 @@ void pkgProblemResolver::MakeScores()
          essantial package above most other packages but low enough
 	 to allow an obsolete essential packages to be removed by
 	 a conflicts on a powerfull normal package (ie libc6) */
-      if ((I->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
+      if ((I->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential
+	  || (I->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important)
 	 Score += PrioEssentials;
 
       // We transform the priority
@@ -631,7 +632,8 @@ void pkgProblemResolver::MakeScores()
    {
       if ((Flags[I->ID] & Protected) != 0)
 	 Scores[I->ID] += AddProtected;
-      if ((I->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
+      if ((I->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential ||
+          (I->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important)
 	 Scores[I->ID] += AddEssential;
    }
 }
@@ -1430,6 +1432,13 @@ static int PrioComp(const void *A,const void *B)
    if ((L.ParentPkg()->Flags & pkgCache::Flag::Essential) != pkgCache::Flag::Essential &&
        (R.ParentPkg()->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
      return -1;
+
+   if ((L.ParentPkg()->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important &&
+       (R.ParentPkg()->Flags & pkgCache::Flag::Important) != pkgCache::Flag::Important)
+     return 1;
+   if ((L.ParentPkg()->Flags & pkgCache::Flag::Important) != pkgCache::Flag::Important &&
+       (R.ParentPkg()->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important)
+     return -1;
    
    if (L->Priority != R->Priority)
       return R->Priority - L->Priority;

apt-pkg/depcache.cc

@@ -963,6 +963,13 @@ struct CompareProviders {
 	 else if ((B->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
 	    return true;
       }
+      if ((A->Flags & pkgCache::Flag::Important) != (B->Flags & pkgCache::Flag::Important))
+      {
+	 if ((A->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important)
+	    return false;
+	 else if ((B->Flags & pkgCache::Flag::Important) == pkgCache::Flag::Important)
+	    return true;
+      }
       // higher priority seems like a good idea
       if (AV->Priority != BV->Priority)
 	 return AV->Priority < BV->Priority;
@@ -1641,6 +1648,7 @@ bool pkgDepCache::MarkRequired(InRootSetFunc &userFunc)
    {
       if(!(PkgState[p->ID].Flags & Flag::Auto) ||
 	  (p->Flags & Flag::Essential) ||
+	  (p->Flags & Flag::Important) ||
 	  userFunc.InRootSet(p) ||
 	  // be nice even then a required package violates the policy (#583517)
 	  // and do the full mark process also for required packages

apt-pkg/packagemanager.cc

@@ -486,7 +486,8 @@ bool pkgPackageManager::EarlyRemove(PkgIterator Pkg)
 
    // Essential packages get special treatment
    bool IsEssential = false;
-   if ((Pkg->Flags & pkgCache::Flag::Essential) != 0)
+   if ((Pkg->Flags & pkgCache::Flag::Essential) != 0 ||
+       (Pkg->Flags & pkgCache::Flag::Important) != 0)
       IsEssential = true;
 
    /* Check for packages that are the dependents of essential packages and 
@@ -496,7 +497,8 @@ bool pkgPackageManager::EarlyRemove(PkgIterator Pkg)
       for (DepIterator D = Pkg.RevDependsList(); D.end() == false &&
 	   IsEssential == false; ++D)
 	 if (D->Type == pkgCache::Dep::Depends || D->Type == pkgCache::Dep::PreDepends)
-	    if ((D.ParentPkg()->Flags & pkgCache::Flag::Essential) != 0)
+	    if ((D.ParentPkg()->Flags & pkgCache::Flag::Essential) != 0 ||
+	        (D.ParentPkg()->Flags & pkgCache::Flag::Important) != 0)
 	       IsEssential = true;
    }
 

debian/changelog

@@ -42,6 +42,9 @@ apt (0.8.16~exp13) UNRELEASED; urgency=low
     - Set the Essential flag on APT instead of only Important
   * apt-pkg/packagemanager.cc:
     - Do not use immediate configuration for packages with the Important flag
+  * Treat the Important flag like the Essential flag with two differences:
+    - No Immediate configuration (see above)
+    - Not automatically installed during dist-upgrade
 
  -- David Kalnischkies <kalnischkies@gmail.com>  Mon, 30 Jan 2012 19:17:09 +0100