-# Parallel defaults to "unset" unless unavailable --jobserver-fds is detected
-# in MAKEFLAGS. This typically means dpkg-buildpackage was called with a -jX
-# option. Then -jX in MAKEFLAGS gets "consumed" by make invocation of
-# debian/rules and "converted" to --jobserver-fds. If jobserver is
-# unavailable, dh was probably called via debian/rules without "+" prefix (so
-# make has closed jobserver FDs). In such a case, MAKEFLAGS is cleaned from the
-# offending --jobserver-fds option in order to prevent further make invocations
-# from spitting warnings and disabling job support.
+# If make was using a jobserver, but it is not available, clean out
+# MAKEFLAGS so that further make invocations can start a new job
+# server.