Reset candidate version explicitly for internal state-keeping

For a (partially) installed package like the one MarkInstall operates on
at the moment we want to discard the candidate from, we have to first
remove the package from the internal state keeping to have proper broken
counts and such and only then reset the candidate version which is a
trivial operation in comparison.

Take a look at the testcase: Now, what is the problem? Correct,
git:i386. Didn't see that coming, right? It is M-A:foreign so apt tries
to switch the architecture of git here (which is pointless, it knows
that this won't work, but lets fix that in another commit) will
eventually realize that it can't install it and wants to discard the
candidate of git:i386 first removing the broken indication like it
should, removing the install flag and then reapplies the broken
indication: Expect it doesn't as it wants to do that over the candidate
version which the package no longer had so seemingly nothing is broken.

It is a bit of a hairball to figure out which commit it is exactly that
is wrong here as they are all influencing each other a bit, but >= 2.1
is an acceptable ballpark. Bisect says 57df273 but that is mostly a lie.

Closes: #961266

1 files changed, 16 insertions, 12 deletions

diff --git a/apt-pkg/depcache.cc b/apt-pkg/depcache.cc
index 842630ec6..02a80b2e8 100644
--- a/apt-pkg/depcache.cc
+++ b/apt-pkg/depcache.cc
@@ -1111,7 +1111,15 @@ bool pkgDepCache::MarkInstall_StateChange(pkgCache::PkgIterator const &Pkg, bool
    return true;
 }
 									/*}}}*/
-bool pkgDepCache::MarkInstall_Discard(pkgCache::PkgIterator const &Pkg)	/*{{{*/
+static bool MarkInstall_DiscardCandidate(pkgDepCache &Cache, pkgCache::PkgIterator const &Pkg) /*{{{*/
+{
+   auto &State = Cache[Pkg];
+   State.CandidateVer = State.InstallVer;
+   State.Update(Pkg, Cache);
+   return true;
+}
+									/*}}}*/
+bool pkgDepCache::MarkInstall_DiscardInstall(pkgCache::PkgIterator const &Pkg) /*{{{*/
 {
    StateCache &State = PkgState[Pkg->ID];
    if (State.Mode == ModeKeep && State.InstallVer == State.CandidateVer && State.CandidateVer == Pkg.CurrentVer())
@@ -1119,15 +1127,14 @@ bool pkgDepCache::MarkInstall_Discard(pkgCache::PkgIterator const &Pkg)	/*{{{*/
    RemoveSizes(Pkg);
    RemoveStates(Pkg);
    if (Pkg->CurrentVer != 0)
-      State.InstallVer = State.CandidateVer = Pkg.CurrentVer();
+      State.InstallVer = Pkg.CurrentVer();
    else
-      State.InstallVer = State.CandidateVer = nullptr;
+      State.InstallVer = nullptr;
    State.Mode = ModeKeep;
-   State.Update(Pkg, *this);
    AddStates(Pkg);
    Update(Pkg);
    AddSizes(Pkg);
-   return true;
+   return MarkInstall_DiscardCandidate(*this, Pkg);
 }
 									/*}}}*/
 static bool MarkInstall_CollectDependencies(pkgDepCache const &Cache, pkgCache::VerIterator const &PV, std::vector<pkgCache::DepIterator> &toInstall, std::vector<pkgCache::DepIterator> &toRemove) /*{{{*/
@@ -1202,7 +1209,7 @@ static bool MarkInstall_MarkDeleteForNotUpgradeable(pkgDepCache &Cache, bool con
    }
    if (propagateProctected)
    {
-      State.CandidateVer = nullptr;
+      MarkInstall_DiscardCandidate(Cache, Pkg);
       Cache.MarkProtected(Pkg);
    }
    return true;
@@ -1230,10 +1237,7 @@ static bool MarkInstall_RemoveConflictsIfNotUpgradeable(pkgDepCache &Cache, bool
 	    }
 	    else if (propagateProctected)
 	    {
-	       if (Pkg->CurrentVer != 0)
-		  State.CandidateVer = Pkg.CurrentVer();
-	       else
-		  State.CandidateVer = nullptr;
+	       MarkInstall_DiscardCandidate(Cache, Pkg);
 	       if (Pkg->CurrentVer == 0)
 		  Cache.MarkProtected(Pkg);
 	    }
@@ -1491,7 +1495,7 @@ bool pkgDepCache::MarkInstall(PkgIterator const &Pkg, bool AutoInst,
    {
       if (failEarly)
       {
-	 MarkInstall_Discard(Pkg);
+	 MarkInstall_DiscardInstall(Pkg);
 	 return false;
       }
       hasFailed = true;
@@ -1519,7 +1523,7 @@ bool pkgDepCache::MarkInstall(PkgIterator const &Pkg, bool AutoInst,
    {
       if (failEarly)
       {
-	 MarkInstall_Discard(Pkg);
+	 MarkInstall_DiscardInstall(Pkg);
 	 return false;
       }
       hasFailed = true;