tests: show IMM is broken when merging file empty in destination
When we are doing in-memory merging, and we are merging a file which is empty in
merge destination, it leads to error 'abort: xxx not found in manifest'.
Next patch will fix this error.
Differential Revision: https://phab.mercurial-scm.org/D6307
cat >> $HGRCPATH <<EOF
[extensions]
narrow=
[ui]
ssh=python "$RUNTESTDIR/dummyssh"
[experimental]
changegroup3 = True
EOF