RFR: Fix webrev generation issue when a source hunk is empty

[Robin Westberg via github.com]

Hi all,

Please review this fix for an index-out-of-bounds when generating a webrev containing an empty source hunk.

Best regards,
Robin

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Commits:
 - 7b7cfaf4:	Fix webrev generation issue when a source hunk is empty, add a reproducing test

Pull request:
https://git.openjdk.java.net/skara/pull/51

Webrev:
https://webrevs.openjdk.java.net/skara/51/webrev.00

Patch:
https://git.openjdk.java.net/skara/pull/51.diff

Fetch command:
git fetch https://git.openjdk.java.net/skara pull/51/head:pull/51