Don't include package in the transitive dependency list.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

cabal-install/Distribution/Client/InstallPlan.hs

@@ -404,11 +404,14 @@ failed pkgid buildResult buildResult' plan = assert (invariant plan') plan'
                             $ packagesThatDependOn plan pkgid ]
 
 -- | Lookup the reachable packages in the reverse dependency graph.
+-- Does NOT include the package for @pkgid@!
 --
-packagesThatDependOn :: GenericInstallPlan ipkg srcpkg iresult ifailure
+packagesThatDependOn :: (HasUnitId ipkg, HasUnitId srcpkg)
+                     => GenericInstallPlan ipkg srcpkg iresult ifailure
                      -> UnitId
                      -> [GenericPlanPackage ipkg srcpkg iresult ifailure]
-packagesThatDependOn plan pkgid = case Graph.revClosure (planIndex plan) [pkgid] of
+packagesThatDependOn plan pkgid = filter ((/= pkgid) . installedUnitId)
+                                $ case Graph.revClosure (planIndex plan) [pkgid] of
                                     Nothing -> []
                                     Just r -> r
 

cabal-install/tests/IntegrationTests2/regression/3324/q/q.cabal

@@ -7,4 +7,3 @@ library
   exposed-modules: Q
   build-depends: base
   -- missing a dep on p here, so expect failure initially
-