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
set -e
set -x
# skip commit logs
HGMERGE=tkmerge; export HGMERGE
EDITOR=true; export EDITOR
rm -rf m m1 m2
mkdir m
cd m
echo "m this that"
echo "this" > a
echo "that" > b
hg init
hg addremove
hg commit
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ..
echo "m2 this that "
mkdir m2
cd m2
hg branch ../m
hg checkout
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m
echo "m this1 that "
echo "this1" > a
hg commit
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ..
echo "m1 this1 that "
mkdir m1
cd m1
hg branch ../m
hg checkout
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m1
echo "m1 this1 that1"
echo "that1" > b
hg commit
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m2
echo "m2 this that2"
echo "that2" > b
hg commit
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m1
echo "m1:m2 this1 that1 that2"
hg merge ../m2 # b should conflict, a should be fine
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m2
echo "m2 this2 that2"
echo "this2" > a
hg commit
echo "a:" `hg dump a` "b:" `hg dump b`
echo
cd ../m2
echo "m2:m this12 that2"
hg merge ../m # a should conflict, b should be fine
echo "a:" `hg dump a` "b:" `hg dump b`
echo
# now here's the interesting bit
# if we choose ancestor by file, no conflicts
# otherwise we've got two equally close ancestors, each with a conflict
# if we go back to the root, we'll have both conflicts again
echo "m2:m1 this12 that12"
hg merge ../m1 # should be clean
echo "a:" `hg dump a` "b:" `hg dump b`
echo