tests/test-filebranch

Fix long-standing excessive file merges

Since switching to the multihead approach, we've been creating
excessive file-level merges where files are marked as merged with
their ancestors.

This explicitly checks at commit time whether the two parent versions
are linearly related, and if so, reduces the file check-in to a
non-merge. Then the file is compared against the remaining parent,
and, if equal, skips check-in of that file (as it's not changed).

Since we're not checking in all files that were different between
versions, we no longer need to mark so many files for merge. This
removes most of the 'm' state marking as well.

Finally, it is possible to do a tree-level merge with no file-level
changes. This will happen if one user changes file A and another
changes file B. Thus, if we have have two parents, we allow commit to
proceed even if there are no file-level changes.

#!/bin/sh

# This test makes sure that we don't mark a file as merged with its ancestor
# when we do a merge.

cat <<'EOF' > merge
#!/bin/sh
echo merging for `basename $1`
EOF
chmod +x merge

echo creating base
hg init a
cd a
echo 1 > foo
echo 1 > bar
echo 1 > baz
echo 1 > quux
hg add foo bar baz quux
hg commit -m "base" -d "0 0"

cd ..
hg clone a b

echo creating branch a
cd a
echo 2a > foo
echo 2a > bar
hg commit -m "branch a" -d "0 0"

echo creating branch b

cd ..
cd b
echo 2b > foo
echo 2b > baz
hg commit -m "branch b" -d "0 0"

echo "we shouldn't have anything but n state here"
hg debugstate | cut -b 1-16,35-

echo merging
hg pull ../a
env HGMERGE=../merge hg update -vm --debug

echo 2m > foo
echo 2b > baz
echo new > quux

echo "we shouldn't have anything but foo in merge state here"
hg debugstate | cut -b 1-16,35- | grep "^m"

hg ci -m "merge" -d "0 0"

echo "main: we should have a merge here"
hg debugindex .hg/00changelog.i

echo "foo: we should have a merge here"
hg debugindex .hg/data/foo.i

echo "bar: we shouldn't have a merge here"
hg debugindex .hg/data/bar.i

echo "baz: we shouldn't have a merge here"
hg debugindex .hg/data/baz.i

echo "quux: we shouldn't have a merge here"
hg debugindex .hg/data/quux.i

echo "everything should be clean now"
hg status

hg verify