git-debrebase: comment: explain why tagged linear anchors are evil

[dgit.git] / git-debrebase

diff --git a/git-debrebase b/git-debrebase
index 59b15aa38045ef8a79e7bc2b9cfd5ef0093b64b7..524631787575bb459556a696c92850e040a8b970 100755 (executable)
--- a/git-debrebase
+++ b/git-debrebase
@@ -396,6 +396,15 @@ sub classify ($) {
        # BreakwaterStart commits are also anchors in the terminology
        # of git-debrebase(5), but they are untagged (and always
        # manually generated).
+       #
+       # We cannot not tolerate any tagged linear commit (ie,
+       # BreakwaterStart commits tagged `[anchor:') because such a
+       # thing could result from an erroneous linearising raw git
+       # rebase of a merge anchor.  That would represent a corruption
+       # of the branch. and we want to detect and reject the results
+       # of such corruption before it makes it out anywhere.  If we
+       # reject it here then we avoid making the pseudomerge which
+       # would be needed to push it.
 
        my $badanchor = sub { $unknown->("git-debrebase \`anchor' but @_"); };
        @p == 2 or return $badanchor->("has other than two parents");
@@ -1234,6 +1243,10 @@ sub cmd_new_upstream_v0 () {
  "[git-debrebase anchor: new upstream $new_upstream_version, merge]",
             ];
 
+       my $clogsignoff = cmdoutput qw(git show),
+           '--pretty=format:%an <%ae>  %aD',
+           $new_bw;
+
        # Now we have to add a changelog stanza so the Debian version
        # is right.
        die if unlink "debian";
@@ -1250,7 +1263,7 @@ $p ($new_version) UNRELEASED; urgency=medium
 
   * Update to new upstream version $new_upstream_version.
 
- -- 
+ -- $clogsignoff
 
 END
        close CN or die $!;