the existing patches were not made by git-debrebase,
using dgit quilt-fixup instead should succeed.
+=item git-debrebase convert-from-unapplied [<upstream-commit-ish>]
+
=item git-debrebase convert-from-gbp [<upstream-commit-ish>]
Cnnverts any of the following into a git-debrebase interchange branch:
=back
+(These two commands operate identically and are simply aliases.)
+
The conversion is done by generating a new anchor merge,
converting any quilt patches as a delta queue,
and dropping the patches from the tree.