dgit: --overwrite now no longer crashes if there is no $archive_hash

Ie there is nothing to overwrite (eg, when used with --new).  Instead,
it is simply ignored, as it is ignored in situations where the push is
fast forward.

Closes:#863576.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

2 files changed, 5 insertions, 1 deletions

diff --git a/debian/changelog b/debian/changelog
index b34b4a0..437bd53 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -14,6 +14,9 @@ dgit (5.2~) unstable; urgency=medium
     happes to be a noop) but --dry-run was specified, fail with an
     explanation, rather than looping with a false coplaint about git
     fetch.  Closes:#871317.
+  * --overwrite now no longer crashes if there is nothing to overwrite
+    (eg, when used with --new).  Instead, it is simply ignored, as it is
+    ignored in situations where the push is fast forward.  Closes:#863576.
 
   test suite:
   * Use nproc(1) rather than Sys::CPU.  This is more portable and does not
diff --git a/dgit b/dgit
index 3409e18..5a6b2b6 100755
--- a/dgit
+++ b/dgit
@@ -4301,7 +4301,8 @@ END
 	}
     }
 
-    if (defined $overwrite_version && !defined $maintviewhead) {
+    if (defined $overwrite_version && !defined $maintviewhead
+	&& $archive_hash) {
 	$dgithead = plain_overwrite_pseudomerge($clogp,
 						$dgithead,
 						$archive_hash);