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
mkdir t
cd t
hg init
echo "[merge]" >> .hg/hgrc
echo "followcopies = 1" >> .hg/hgrc
echo foo > a
echo foo > a2
hg add a a2
hg ci -m "start" -d "0 0"
hg mv a b
hg mv a2 b2
hg ci -m "rename" -d "0 0"
echo "checkout"
hg co 0
echo blahblah > a
echo blahblah > a2
hg mv a2 c2
hg ci -m "modify" -d "0 0"
echo "merge"
hg merge -y --debug
hg status -AC
cat b
hg ci -m "merge" -d "0 0"
hg debugindex .hg/store/data/b.i
hg debugrename b