[PATCH] rebase: pass --signoff option to git am

@@ -385,6 +385,11 @@ have the long commit hash prepended to the format.
 	Recreate merge commits instead of flattening the history by replaying
 	commits a merge commit introduces. Merge conflict resolutions or manual
 	amendments to merge commits are not preserved.
+
+--signoff::
+	This flag is passed to 'git am' to sign off all the rebased
+	commits (see linkgit:git-am[1]).
+
 +
 This uses the `--interactive` machinery internally, but combining it
 with the `--interactive` option explicitly is generally not a good

@@ -34,6 +34,7 @@
 autosquash         move commits that begin with squash!/fixup! under -i
 committer-date-is-author-date! passed to 'git am'
 ignore-date!       passed to 'git am'
+signoff!           passed to 'git am'
 whitespace=!       passed to 'git apply'
 ignore-whitespace! passed to 'git apply'
 C=!                passed to 'git apply'

@@ -321,7 +322,7 @@ run_pre_rebase_hook ()
 	--ignore-whitespace)
 		git_am_opt="$git_am_opt $1"
 		;;
-	--committer-date-is-author-date|--ignore-date)
+	--committer-date-is-author-date|--ignore-date|--signoff)
 		git_am_opt="$git_am_opt $1"
 		force_rebase=t
 		;;