X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=dgit.git;a=blobdiff_plain;f=git-debrebase;h=d80c8d35bb1875e509f658077eb3a1ed7cb7c69a;hp=f09508e1be90c859c60aa8a0220b1891853e86aa;hb=8f28dfa084b6d63e385d7fe538214eee2f90ea9e;hpb=6a3fc22a4ad2b36bd799b1f9e3b7d65dcd4a6839

diff --git a/git-debrebase b/git-debrebase
index f09508e1..d80c8d35 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -433,9 +433,10 @@ sub ffq_prev_branchinfo () {
     return gdr_ffq_prev_branchinfo($current);
 }
 
-sub record_gdrlast ($$) {
-    my ($gdrlast, $newvalue) = @_;
-    push @deferred_updates, "update $gdrlast $newvalue $git_null_obj";
+sub record_gdrlast ($$;$) {
+    my ($gdrlast, $newvalue, $oldvalue) = @_;
+    $oldvalue ||= $git_null_obj;
+    push @deferred_updates, "update $gdrlast $newvalue $oldvalue";
 }
 
 sub gbp_pq_export ($$$) {
@@ -2411,6 +2412,13 @@ sub check_series_has_all_patches ($) {
 
 sub begin_convert_from () {
     my $head = get_head();
+    my ($ffqs, $ffqm, $symref, $ffq_prev, $gdrlast) = ffq_prev_branchinfo();
+
+    fail "ffq-prev exists, this is already managed by git-debrebase!"
+	if $ffq_prev && git_get_ref $ffq_prev;
+    snag 'already-converted',
+	"ahead of debrebase-last, this is already managed by git-debrebase!"
+	if $gdrlast && git_get_ref $gdrlast && is_fast_fwd $gdrlast, $head;
     return ($head, undef);
 }