merge: refactor unknown file conflict checking
Previously, we would do a full working directory walk including
unknown files to perform a merge. In many cases, this was painful
because unknown files greatly outnumbered tracked files and generally
had no useful effect on the merge.
Here we instead wait until we find a file in the destination that's
not tracked locally and detect if it exists and is not ignored. This
is usually cheaper but can be -more- expensive in the case where we're
adding a huge number of files. On the other hand, the cost of statting
the new files should be dwarfed by the cost of eventually writing
them.
In this version, case collisions are detected implicitly by
os.path.exists and wctx[f] lookup.
update: use normal update path with --check (
issue2450)
This avoids clobbering unknown files on update by not using overwrite mode.
fetch: use update rather than clean when updating (
issue3246)
We already verify the working directory is "clean" before starting so
there's no advantage to clobbering the working directory.
mdiff: adjust hunk offsets with --ignore-blank-lines (
issue3234)
When diffing the following documents with --ignore-blank-lines (-B):
$ cat > a <<EOF
>
>
>
> b
> x
> d
> EOF
and:
$ cat > b <<EOF
> b
> y
> d
> EOF
the context lines are taken from the first document, even if the lines differ
(with -w or -b) or if the number of lines differ (with -B). In the second case,
we have to adjust the hunk new lines offsets or we end with inconsistent diffs
like (see the @@ offsets):
diff -r
0e66aa54f318 a
--- a/a
+++ b/a
@@ -1,4 +1,3 @@
b
-x
+y
d
Note that having different context lines in a and b means the diff can be
applied but is not invertible.
Reported by Nicholas Riley <com-selenic@sabi.net>