From 81e93ac2f3ac0b129f0d5e77d055b99053105892 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 8 Jul 2018 20:05:26 +0100
Subject: [PATCH 1/1] git-debrebase convert-from-gbp: Add ffq check

Check that the result will not count as having diverged.  This will
usually turn failures to make the ff pseudomerge into -fdiverged.

Related to #903132.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 debian/changelog    | 3 +++
 git-debrebase       | 4 +++-
 git-debrebase.1.pod | 4 ++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/debian/changelog b/debian/changelog
index 82f6acc6..0afe46a2 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,6 +2,9 @@ dgit (5.9~) unstable; urgency=medium
 
   * git-debrebase convert-from-gbp: Look for dgit-generated tags so we can
     usually make the new branch ff of the dgit view.  Closes:#903132.
+  * git-debrebase convert-from-gbp: Check that the result will not
+    count as having diverged.  This will usually turn failures to make
+    the ff pseudomerge into -fdiverged.  Related to #903132.
 
  --
 
diff --git a/git-debrebase b/git-debrebase
index 7b2e4f31..f0022252 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -1658,7 +1658,7 @@ sub cmd_convert_from_gbp () {
 	print STDERR "cannot stitch in dgit view: $@\n";
     }
 
-    snags_maybe_bail();
+    snags_maybe_bail_early();
 
     my $work;
 
@@ -1696,6 +1696,8 @@ sub cmd_convert_from_gbp () {
 	}
     };
 
+    ffq_check $work;
+    snags_maybe_bail();
     update_head_checkout $old_head, $work, 'convert-from-gbp';
 }
 
diff --git a/git-debrebase.1.pod b/git-debrebase.1.pod
index d67e5570..273ef47d 100644
--- a/git-debrebase.1.pod
+++ b/git-debrebase.1.pod
@@ -265,6 +265,10 @@ your new git-debrebase view is appropriately fast forward.
 The result is a well-formed git-debrebase interchange branch.
 The result is also fast-forward from the gbp branch.
 
+It is a snag if the new branch looks like it will have diverged,
+just as for a laundering/unstitching call to git-debrebase;
+See L</Establish the current branch's ffq-prev>, below.
+
 Note that it is dangerous not to know whether you are
 dealing with a gbp patches-unappled branch containing quilt patches,
 or a git-debrebase interchange branch.
-- 
2.30.2