merge: do early copy to deal with issue636 Without copies/renames, merges source names are 1:1 with their targets. Copies and renames introduce the possibility that there will be two merges with the same input but different output. By doing the copy to the destination name before the merge, the actual merge becomes 1:1 again, and no source is the input to two different merges. - add a preliminary scan to applyupdates to do copies - for the merge action, pass the old name (for finding ancestors) and the new name (for input to the merge) to filemerge - eliminate the old post-merge copy - lookup file contents from new name in filemerge - pass new name to external merge helper - report merge failure at new name - add a test

#!/bin/sh

mkdir t
cd t
hg init
echo "added file1" > file1
echo "another line of text" >> file1
echo "added file2" > file2
hg add file1 file2
hg commit -m "added file1 and file2" -d "1000000 0" -u user
echo "changed file1" >> file1
hg commit -m "changed file1" -d "1000000 0" -u user
hg -q log
hg id
hg update -C 0
hg id
echo "changed file1" >> file1
hg id
hg revert --no-backup --all
hg diff
hg status
hg id
hg update
hg diff
hg status
hg id
hg update -C 0
echo "changed file1 different" >> file1
hg update
hg diff --nodates
hg status
hg id
hg revert --no-backup --all
hg diff
hg status
hg id
hg revert -r tip --no-backup --all
hg diff
hg status
hg id
hg update -C
hg diff
hg status
hg id