tests/narrow-library.sh

remotefilelog: log when we're about to fetch files

I'm debugging a slow client situation and knowing how many files are
in the batch request would be a nice thing.

Differential Revision: https://phab.mercurial-scm.org/D6353

cat >> $HGRCPATH <<EOF
[extensions]
narrow=
[ui]
ssh=python "$RUNTESTDIR/dummyssh"
[experimental]
changegroup3 = True
EOF