Use pre-packaged Python libraries instead of /usr

Change-Id: If27064f17c243ab1b0c98957a013eb86a37b5cb0
diff --git a/debian/slycot.BUILD b/debian/slycot.BUILD
index 0122f5d..9853c40 100644
--- a/debian/slycot.BUILD
+++ b/debian/slycot.BUILD
@@ -71,8 +71,8 @@
   ],
   deps = [
     ':slicot',
-    '@usr_repo//:python2.7_lib',
-    '@usr_repo//:python2.7_f2py',
+    '@python_repo//:python2.7_lib',
+    '@python_repo//:python2.7_f2py',
   ],
   copts = [
     '-Wno-error',