RFR Mercurial trees extension: Fixes for hg 4.2-4.5

[mark.reinhold at oracle.com]

http://cr.openjdk.java.net/~mr/rev/trees/

Tested against hg 1.1-4.5, including remote tests.

Question: In some of the code-tools repos, some changeset comments
include bug numbers from the CODETOOLS JBS project.  A couple of the
recent changesets in the trees repo have bug numbers, but the most
recent one does not.

Do we want to use CODETOOLS bug numbers in the trees repo uniformly,
going forward?  What about other hg-tools repos?

Personally, it seems like overkill to me since these tools are small,
and usually change only rarely, but I'd like to hear other opinions.

- Mark