undo-files: cleanup backup when cleaning undos
Previously, the backups were left behind, by operation cleaning the undo's like
strip, narrow and stream clone.
The remaining elevant in the room is the transaction itself, who does not
properly cleanup undo backup before copying the new ones.
$ cat > unix2mac.py <<EOF
> import sys
>
> for path in sys.argv[1:]:
> data = open(path, 'rb').read()
> data = data.replace(b'\n', b'\r')
> open(path, 'wb').write(data)
> EOF
$ hg init
$ echo '[hooks]' >> .hg/hgrc
$ echo 'pretxncommit.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
$ echo 'pretxnchangegroup.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
$ cat .hg/hgrc
[hooks]
pretxncommit.cr = python:hgext.win32text.forbidcr
pretxnchangegroup.cr = python:hgext.win32text.forbidcr
$ echo hello > f
$ hg add f
$ hg ci -m 1
$ "$PYTHON" unix2mac.py f
$ hg ci -m 2
attempt to commit or push text file(s) using CR line endings
in dea860dc51ec: f
transaction abort!
rollback completed
abort: pretxncommit.cr hook failed
[40]
$ hg cat f | f --hexdump
0000: 68 65 6c 6c 6f 0a |hello.|
$ f --hexdump f
f:
0000: 68 65 6c 6c 6f 0d |hello.|