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

0 files updated, 0 files merged, 1 files removed, 0 files unresolved
changeset:   2:62ec0e86d1e5
tag:         tip
parent:      0:567dde5e6e98
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     add empty3

changeset:   1:41ab7b321727
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     add empty2

1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
M empty2
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty1
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty2
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty3