Merge tag 'debian/6.6' into stretch-bpo

dgit release 6.6 for unstable (sid) [dgit]
[dgit distro=debian]

# gpg: Signature made Sun 05 Aug 2018 10:43:37 BST
# gpg:                using RSA key 559AE46C2D6B6D3265E7CBA1E3E3392348B50D39
# gpg: Can't check signature: No public key

1 files changed, 42 insertions, 0 deletions

diff --git a/git-debrebase.5.pod b/git-debrebase.5.pod
index 52fb60b..d39ad94 100644
--- a/git-debrebase.5.pod
+++ b/git-debrebase.5.pod
@@ -487,6 +487,48 @@ These patch files can be stripped out and/or regenerated as needed.
 
 =back
 
+=head1 ILLEGAL OPERATIONS
+
+Some git operations are not permitted in this data model.
+Performing them will break git-debrebase.
+
+=over
+
+=item General merges
+
+See L</OTHER MERGES>, above.
+
+=item git-rebase starting too soon, or without base argument
+
+git-rebase must not be invoked in such a way that
+the chosen base is before the anchor,
+or before the last pseudomerge.
+This is because git-rebase mangles merges.
+git rebase --preserve-merges is also dangerous.
+
+git-rebase without a base argument will often start too early.
+
+For these reasons,
+it is better to use git-debrebase and
+let it choose the base
+for your rebase.
+If you do realise you have make this mistake,
+it is best to use the reflog to recover to a suitable
+good previous state.
+
+=item Editing debian/patches
+
+debian/patches is an output from git-debrebase,
+not an input.
+If you edit patches git-debrebase will complain
+and refuse to work.
+If you add patches your work is likely to be discarded.
+
+Instead of editing patches,
+use git-debrebase to edit the corresponding commits.
+
+=back
+
 =head1 COMMIT MESSAGE ANNOTATIONS
 
 git-debrebase makes annotations