tree 134efc3f0c6df8805820be6807f75881a1c8ad4a
parent 36d87e549a4294c1697d68a0160383153b8f7891
author Jonathan Nieder <jrn@google.com> 1376334584 -0700
committer Jonathan Nieder <jrn@google.com> 1376334584 -0700

Do not try to create review notes for ref deletion events

The reviewnotes plugin already handles an all-zeroes oldObjectId by
not including a negative commit for it in the revwalk.  An all-zeroes
newObjectId represents a ref deletion, which represents no new history
so the revwalk can be skipped altogether.

Noticed by reading logs.

	Missing unknown 0000000000000000000000000000000000000000
	org.eclipse.jgit.errors.MissingObjectException: Missing unknown 0000000000000000000000000000000000000000
		at org.eclipse.jgit.internal.storage.dfs.DfsReader.open(DfsReader.java:219)
		at org.eclipse.jgit.lib.ObjectReader.open(ObjectReader.java:229)
		at org.eclipse.jgit.revwalk.RevWalk.parseAny(RevWalk.java:809)
		at org.eclipse.jgit.revwalk.RevWalk.parseCommit(RevWalk.java:722)
		at com.googlesource.gerrit.plugins.reviewnotes.CreateReviewNotes.createNotes(CreateReviewNotes.java:122)
		at com.googlesource.gerrit.plugins.reviewnotes.RefUpdateListener.createReviewNotes(RefUpdateListener.java:126)
		at com.googlesource.gerrit.plugins.reviewnotes.RefUpdateListener.access$000(RefUpdateListener.java:38)
		at com.googlesource.gerrit.plugins.reviewnotes.RefUpdateListener$1.run(RefUpdateListener.java:66)

Change-Id: I4151d45674f92ed1d034ea3adadc48c49a686f03