diff: check changes for strict equality

Otherwise there are possible cases, when Change is substituted by another one with same path (therefore equals()), but different content.

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/CacheChangeProcessor.java

@@ -194,7 +194,7 @@ public abstract class CacheChangeProcessor extends DiffRequestProcessor {
       return;
     }
 
-    if (myCurrentChange.getBeforeRevision() instanceof FakeRevision || myCurrentChange.getAfterRevision() instanceof FakeRevision) {
+    if (!ChangeDiffRequestProducer.isEquals(myCurrentChange, selectedChange)) {
       myCurrentChange = selectedChange;
       updateRequest();
     }