If a revision is specified in a way that looks like a commit hash, Lix expects
that it actually is a commit hash. Unlike Git, Mercurial will fall back to
bookmarks, tags and branches with the specified name when a commit with the
specified hash does not exist. Previously, an assertion failure would be thrown
due to the resulting commit hash mismatch. Tell Mercurial to only take commit
hashes into account, whose non-existence is then handled gracefully.
Change-Id: I98bf020187575f3cf8176831da85872d066c4d95
Alois Wohlschlager
a2daf4e774