amend: wrap all commit operations in a single transaction
This allows proper recovery of an interrupted amend process.
No changes are made to the logic besides:
- indent operations into a single try-except clause,
- some comment and code wrapping to 80 chars,
- strip logic should not be contained in the transaction and is extracted from
the main code.
$ hg init
$ echo a > a
$ hg ci -Am t
adding a
$ hg mv a b
$ hg ci -Am t1
$ hg debugrename b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
$ hg mv b a
$ hg ci -Am t2
$ hg debugrename a
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
$ hg debugrename --rev 1 b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3