-sub read_tree_upstream ($;$) {
- my ($treeish, $keep_patches) = @_;
- my $save = cmdoutput @git, qw(write-tree --prefix=debian/);
+sub read_tree_upstream ($;$$) {
+ my ($treeish, $keep_patches, $tree_with_debian) = @_;
+ # if $tree_with_debian is supplied, will use that for debian/
+ # otherwise will save and restore it.
+ my $debian =
+ $tree_with_debian ? "$tree_with_debian:debian"
+ : cmdoutput @git, qw(write-tree --prefix=debian/);