commit: try hard to reuse p1 manifest if nothing changed
This is all for commit reproducibility on "hg convert".
With this change, p1 manifest is reused if ctx.files() *to be committed* is
empty, and if new manifest entry is identical to p1. This is important
property for "hg convert" since memctx.files() built from a convert source
may be either a) more narrowed thanks to a committed ctx.files() which
provides more accurate status, or b) containing redundant files because of
sloppy filtering on e.g. octopus merge.
$ cat <<EOF >> $HGRCPATH
> [extensions]
> purge =
> EOF
$ hg init test
$ cd test
$ echo a > changed
$ echo a > removed
$ echo a > source
$ hg ci -Am addfiles
adding changed
adding removed
adding source
$ echo a >> changed
$ echo a > added
$ hg add added
$ hg rm removed
$ hg cp source copied
$ hg diff --git > ../unknown.diff
Test adding on top of an unknown file
$ hg up -qC 0
$ hg purge
$ echo a > added
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
file added already exists
1 out of 1 hunks FAILED -- saving rejects to file added.rej
abort: patch failed to apply
[255]
Test modifying an unknown file
$ hg revert -aq
$ hg purge
$ hg rm changed
$ hg ci -m removechanged
$ echo a > changed
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot patch changed: file is not tracked
[255]
Test removing an unknown file
$ hg up -qC 0
$ hg purge
$ hg rm removed
$ hg ci -m removeremoved
created new head
$ echo a > removed
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot patch removed: file is not tracked
[255]
Test copying onto an unknown file
$ hg up -qC 0
$ hg purge
$ echo a > copied
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot create copied: destination already exists
[255]
$ cd ..