git-if-needed: read patches from a series file.

Change-Id: I29c87e8448f89deaab0c04678296b25013982486
diff --git a/tools/git-if-needed/tests/data/series b/tools/git-if-needed/tests/data/series
new file mode 100644
index 0000000..fbb68d7
--- /dev/null
+++ b/tools/git-if-needed/tests/data/series
@@ -0,0 +1,4 @@
+openstack/cinder/add-readme.patch
+openstack/cinder/modify-readme.patch
+openstack/nova/add-readme.patch
+openstack/cinder/another-file.patch