Only skip openstack tarballs in requirements check

We really only want to allow openstack tarball requirements to be added
without checking, not just any tarball.

Change-Id: I0ce458c95dc2fba07100b921d094ff174ed7da57
Reviewed-on: https://review.openstack.org/36070
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Khai Do <zaro0508@gmail.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins

modules/jenkins/files/slave_scripts/project-requirements-change.py

@@ -44,7 +44,7 @@ class RequirementsList(object):
             line = line[:line.find('#')]
             line = line.strip()
             if (not line or
-                line.startswith('http') or
+                line.startswith('http://tarballs.openstack.org/') or
                 line.startswith('-e') or
                 line.startswith('-f')):
                 continue