merge: print status message before launching external merge tool
It seems somewhat common that people run into a merge conflict and
don't notice the launched merge tool, and instead they think hg just
hung. Let's print a message for each file that we launch a GUI merge
tool for.
#require serve killdaemons
$ hg clone http://localhost:$HGPORT/ copy
abort: * (glob)
[255]
$ test -d copy
[1]
$ python "$TESTDIR/dumbhttp.py" -p $HGPORT --pid dumb.pid
$ cat dumb.pid >> $DAEMON_PIDS
$ hg clone http://localhost:$HGPORT/foo copy2
abort: HTTP Error 404: * (glob)
[255]
$ killdaemons.py