blame: Reuse existing blameEntireRegionOnParent method

Skipping directly to the parent is already possible with an existing
helper method. Update the source path (to follow the rename) and then
use the existing code path to push the parent inside the current entry.

Change-Id: Icb1d49e53d14b599efc478990613625a9e058e09

org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java

@@ -720,10 +720,8 @@ public class BlameGenerator {
 					// have an exact content match. For performance reasons
 					// we choose to follow the one parent over trying to do
 					// possibly both parents.
-					n.sourceCommit = parent;
 					n.setSourcePath(PathFilter.create(r.getOldPath()));
-					push(n);
-					return false;
+					return blameEntireRegionOnParent(n, parent);
 				}
 
 				renames[pIdx] = r;