is synthesized by your local copy of dgit.
It is fast forwarding.
-Debian separates out the security updates, into C<debian-security>.
-Telling dgit C<debian,-security> means that it should include
-any updates available in C<debian-security>.
+Debian separates out the security updates, into C<*-security>.
+Telling dgit C<jessie,-security> means that it should include
+any updates available in C<jessie-security>.
+The comma notation is a request to dgit to track jessie,
+or jessie-security if there is an update for the package there.
(You can also dgit fetch in a tree that wasn't made by dgit clone.
If there's no C<debian/changelog>