Added tests for bug with three-way-merging of old tip, tip and cwd.
+ mkdir t
+ cd t
+ hg init
+ echo 'added file1'
+ echo 'added file2'
+ hg add file1 file2
+ hg commit -m 'added file1 and file2' -d '0 0' -u user
+ echo 'changed file1'
+ hg commit -m 'changed file1' -d '0 0' -u user
+ hg -q log
1:3aa14bbc23d90e3f8b5b639b4a43d76509bae76c
0:8633637036c18f021d771208e16ae3508ab81d28
+ hg id
3aa14bbc23d9 tip
+ hg update -C 0
+ hg id
8633637036c1
+ echo 'changed file1'
+ hg id
8633637036c1+
+ hg revert
+ hg diff
+ hg status
+ hg id
8633637036c1
+ hg update
+ hg diff
+ hg status
+ hg id
3aa14bbc23d9 tip
+ hg update -C 0
+ echo 'changed file1'
+ HGMERGE=merge
+ hg update
merging file1
+ hg diff
+ hg status
+ hg id
3aa14bbc23d9 tip
+ hg revert
+ hg diff
+ hg status
+ hg id
3aa14bbc23d9 tip
+ hg revert -r tip
+ hg diff
+ hg status
+ hg id
3aa14bbc23d9 tip
+ hg update -C
+ hg diff
+ hg status
+ hg id
3aa14bbc23d9 tip
+ cd ..
+ /bin/rm -rf t