RFR: Improve the previous empty hunks fix

[Robin Westberg via github.com]

Hi all,

The previous fix for generating webrevs with empty source hunks broke other cases. Here's more fixes and tests.

Best regards,
Robin

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Commits:
 - e33063e5:	Improve the previous empty hunks fix

Pull request:
https://git.openjdk.java.net/skara/pull/52

Webrev:
https://webrevs.openjdk.java.net/skara/52/webrev.00

Patch:
https://git.openjdk.java.net/skara/pull/52.diff

Fetch command:
git fetch https://git.openjdk.java.net/skara pull/52/head:pull/52