RMG - Add a note about merging the release branch back into blead

I was momentarily confused and almost did the wrong thing when I saw that
"git merge release-5.19.4" had produced a merge commit (71d5a36340),
whereas the merge of 5.19.3 a month ago did not (see f865d60069).

The cause was simply that a change (ac239e1c3e) had been pushed to blead
since I'd created the release branch, which had not happened when merging
the 5.19.3 release branch last month.

diff --git a/Porting/release_managers_guide.pod b/Porting/release_managers_guide.pod
index 0605a08..87ce797 100644 (file)
--- a/Porting/release_managers_guide.pod
+++ b/Porting/release_managers_guide.pod
@@ -1062,6 +1062,12 @@ Merge the (local) release branch back into master now, and delete it.
   git push
   git branch -d release-5.xx.yy
 
+Note: The merge will create a merge commit if other changes have been pushed
+to blead while you've been working on your release branch. Do NOT rebase your
+branch to avoid the merge commit (as you might normally do when merging a
+small branch into blead) since doing so will invalidate the tag that you
+created earlier.
+
 =head3 publish the release tag
 
 Now that you've shipped the new perl release to PAUSE and pushed your changes