convert_git: avoid returning two entries for the same file in getchanges
This could happen in merge changesets if the merged file was different
from both parents.
#!/bin/sh
hg init
echo a > a
hg ci -d '0 0' -Ama
hg an a
echo "[ui]" >> $HGRCPATH
echo "strict=True" >> $HGRCPATH
hg an a
hg annotate a
echo % should succeed - up is an alias, not an abbreviation
hg up