Handle setup_requires in mirror script.

Change-Id: Ice9ccad1dc28ecd5a44430839a374632f9912514
Reviewed-on: https://review.openstack.org/24862
Reviewed-by: Anita Kuno <akuno@lavabit.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
diff --git a/tools/pip-requires b/tools/pip-requires
index e990c7f..4fac6a8 100644
--- a/tools/pip-requires
+++ b/tools/pip-requires
@@ -3,3 +3,4 @@
 paramiko
 PyGithub
 pyyaml
+pkginfo