tests/test-merge-combination-exec-bytes.t

dirstate: invalidate the dirstate change on transaction failure

If the change context lives inside a transaction, the change are not flushed to
disk on exit as this is delegated to the transaction. As a result we should
also delegate the part that do cleanup on failure.

The issue was caught by tests with other change, but it seems useful to fix this
as soon as possible.

Testing recorded "modified" files for merge commit
==================================================

#require execbit

This file shows what hg says are "modified" files for a merge commit
(hg log -T {files}), somewhat exhaustively.

This test file shows merges that involves executable bit changing, check test-merge-combination-exec-bytes.t

For merges that involve files contents changing, check test-merge-combination-file-content.t

For testing of multiple corner case, check test-merge-combination-misc.t

Case with multiple or zero merge ancestors, copies/renames, and identical file contents
with different filelog revisions are not currently covered.

  $ . $TESTDIR/testlib/merge-combination-util.sh

All the merges of executable bit.

  $ range () {
  >   max=a
  >   for i in $@; do
  >     if [ $i = - ]; then continue; fi
  >     if [ $i > $max ]; then max=$i; fi
  >   done
  >   if [ $max = a ]; then echo f; else echo f x; fi
  > }
  $ isgood () { case $line in *f*x*) true;; *) false;; esac; }
  $ createfile () {
  >   if [ -f a ] && (([ -x a ] && [ $v = x ]) || (! [ -x a ] && [ $v != x ]))
  >   then touch $file
  >   else touch a; if [ $v = x ]; then chmod +x a; else chmod -x a; fi
  >   fi
  > }

  $ genmerges
  fffx  : agree on "a"
  ffxf  : agree on "a"
  ffxx  : agree on ""
  ffx-  : agree on "a"
  ff-x  : hg said "", expected "a"
  fxff  : hg said "", expected "a"
  fxfx  : hg said "a", expected ""
  fxf-  : agree on "a"
  fxxf  : agree on "a"
  fxxx  : agree on ""
  fxx-  : agree on "a"
  fx-f  : hg said "", expected "a"
  fx-x  : hg said "", expected "a"
  fx--  : hg said "", expected "a"
  f-fx  : agree on "a"
  f-xf  : agree on "a"
  f-xx  : hg said "", expected "a"
  f-x-  : agree on "a"
  f--x  : agree on "a"
  -ffx  : agree on "a"
  -fxf C: agree on "a"
  -fxx C: hg said "", expected "a"
  -fx- C: agree on "a"
  -f-x  : hg said "", expected "a"
  --fx  : agree on "a"