abump: verify that we're in git tree

abump.in

@@ -95,6 +95,7 @@ cvelist=
 fixes=
 
 [ -n "$APORTSDIR" ] || error "can't locate \$APORTSDIR"
+git rev-parse 2>/dev/null || die "not in a git tree"
 
 args=`getopt -o s:Rkqh --long security:,recursive,keep,quiet,help -n "$prog" -- "$@"`
 if [ $? -ne 0 ]; then