bugzilla: add XMLRPC interface.
Add support for access to Bugzilla via the XMLRPC interface.
This requires a single username and password used to log in to Bugzilla,
plus the URL of the Bugzilla installation. Commit messages are added to
bugs as before, but security only permits them to be added as the
username used to log in.
$ hg init
$ echo 0 > a
$ echo 0 > b
$ hg ci -A -m m
adding a
adding b
$ hg rm a
$ hg cat a
0
$ hg cat --decode a # more tests in test-encode
0
$ echo 1 > b
$ hg ci -m m
$ echo 2 > b
$ hg cat -r 0 a
0
$ hg cat -r 0 b
0
$ hg cat -r 1 a
a: no such file in rev 7040230c159c
[1]
$ hg cat -r 1 b
1