fix prepare-commit for sipify

scripts/prepare-commit.sh

@@ -120,7 +120,7 @@ for f in $MODIFIED; do
     sip_file=$(${GP}sed -r 's/^src\/(core|gui|analysis|server)\///; s/\.h$/.sip/' <<<$f )
     module=$(${GP}sed -r 's/^src\/(core|gui|analysis|server)\/.*$/\1/' <<<$f )
     if grep -Fq "$sip_file" ${TOPLEVEL}/python/${module}/${module}_auto.sip; then
-      sip_file=$(${GP}sed -r 's/^src\///; s/\.h$/.sip/' <<<$f )
+      sip_file=$(${GP}sed -r 's/^src\///; s/\.h$/.sip.in/' <<<$f )
       m=python/$sip_file.$REV.prepare
       touch python/$sip_file
       cp python/$sip_file $m