run-tests: fix _checkhglib() so it's correct when using --with-hg.
Since this makes the warning less likely, upgrade it to a "real"
warning to stderr.
#!/bin/sh
echo "[extensions]" >> $HGRCPATH
echo "bookmarks=" >> $HGRCPATH
echo "[bookmarks]" >> $HGRCPATH
echo "track.current = True" >> $HGRCPATH
hg init
echo % no bookmarks
hg bookmarks
echo % set bookmark X
hg bookmark X
echo % list bookmarks
hg bookmark
echo % update to bookmark X
hg update X
echo % list bookmarks
hg bookmarks
echo % rename
hg bookmark -m X Z
echo % list bookmarks
hg bookmarks
echo % new bookmark Y
hg bookmark Y
echo % list bookmarks
hg bookmark
echo % commit
echo 'b' > b
hg add b
hg commit -m'test'
echo % list bookmarks
hg bookmark
echo % delete bookmarks
hg bookmark -d Y
hg bookmark -d Z
echo % list bookmarks
hg bookmark
echo % update to tip
hg update tip