bug#18714: duping to newer bug

[Mike Frysinger]

forcemerge 20314 18714 18715

looks like this was reported later again, and then resolved & fixed there.
it was released in automake-1.16.
http://git.savannah.gnu.org/cgit/automake.git/commit/?h=7c25c996d1c7c212a5981aa0e9c4434b6f33f7b8