From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Tue, 31 Jul 2018 12:16:53 +0000 (+0100)
Subject: git-debrebase: convert-from-gbp: Use same algorithm for finding upstream
X-Git-Tag: archive/debian/6.3~8
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=dgit.git;a=commitdiff_plain;h=c83cc428208bee99de3b75158b9779449403ee1b;hp=8b650aeb481a3a4cb71325b6b7255194589c7612

git-debrebase: convert-from-gbp: Use same algorithm for finding upstream

The version is in the changelog, and thus upstream commitish can then
be found from as new-upstream.

This also means we now give the same error message, which is much
better than the one we had before.

Closes:#905062.

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

diff --git a/debian/changelog b/debian/changelog
index ef70f6e2..4d6e50af 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -6,6 +6,8 @@ dgit (6.3~) unstable; urgency=medium
     with bad syntax.
   * git-debrebase test suite: Test messages about unprocessable commits.
   * git-debrebase: new-upstream: Fix handling of epochs.
+  * git-debrebase: convert-from-gbp: Use same algorithm for finding
+    upstream commitish as new-upstream.  Closes:#905062.
 
  --
 
diff --git a/git-debrebase b/git-debrebase
index 5d3c7426..2687ef1f 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -1604,11 +1604,18 @@ sub cmd_make_patches () {
 }
 
 sub cmd_convert_from_gbp () {
-    badusage "needs 1 optional argument, the upstream git rev"
+    badusage "want only 1 optional argument, the upstream git commitish"
 	unless @ARGV<=1;
+
+    my $clogp = parsechangelog();
+    my $version = $clogp->{'Version'}
+	// die "missing Version from changelog";
+
     my ($upstream_spec) = @ARGV;
-    $upstream_spec //= 'refs/heads/upstream';
-    my $upstream = git_rev_parse $upstream_spec;
+
+    my ($upstream, $upstream_version) =
+	resolve_upstream_version($upstream_spec, $version);
+
     my $old_head = get_head();
 
     my $upsdiff = get_differs $upstream, $old_head;
diff --git a/git-debrebase.1.pod b/git-debrebase.1.pod
index 273ef47d..b15bf00c 100644
--- a/git-debrebase.1.pod
+++ b/git-debrebase.1.pod
@@ -250,6 +250,8 @@ the gbp upstream branch, if there is one.
 It is a snag if it is not an ancestor of HEAD,
 or if the history between the upstream and HEAD
 contains commits which make changes to upstream files.
+If it is not specified,
+the same algorithm is used as for git-debrebase new-upstream.
 
 It is also a snag if the specified upstream
 has a debian/ subdirectory.