tests/narrow-library.sh

patch: move yielding "\n" to the end of loop

The original logic makes it harder to reason about - it yields the "\n"
character belonging to the last line in the next loop iteration.

The new code is in theory a little bit slower. But is more readable. It
makes the following changes easier to read.

Differential Revision: https://phab.mercurial-scm.org/D3210

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