hgweb: display diff for a changeset against any parents (issue2810)
During merge of branches, it is useful to compare merge results against
the two parents. This change adds this support to hgweb. To specify
which parent to compare to, use rev/12300:12345 where 12300 is a
parent changeset number. Two links are added to changeset web page so
that one can choose which parent to compare to.
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a