CCE with getAdapter

This was a regression in a specific version o EGit that unfortunately
found its way in compare as well.

Porting the fix from EGit commit
0aee49637c6fa6508f7185f61d4f9759789ebd3e

Bug: 579973
Change-Id: Ia821c066a4fc19f85445061fde3016c2c58e7084

plugins/org.eclipse.emf.compare.egit.ui/src/org/eclipse/emf/compare/egit/ui/internal/merge/AbstractGitCompareEditorInput.java

@@ -196,7 +196,7 @@ public <T> T getAdapter(Class<T> adapter) {
 			}
 			return adapter.cast(getShowInSource(null));
 		} else if (adapter == Repository.class) {
-			return adapter.cast(adapter);
+			return adapter.cast(repository);
 		}
 		return super.getAdapter(adapter);
 	}