Issue a warning if "-r ." is used with two working directory parents.
Rationale for not aborting instead:
The first parent is usually more important as it is the local branch
during a merge and commands like 'hg diff' and 'hg diff -r.' behave still
identically (except for the warning of course).
Added a test for log -r. with one and two parents.
#!/bin/sh
echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH
hg init a
cd a
hg qnew first.patch
hg qnew first.patch
touch ../first.patch
hg qimport ../first.patch
exit 0