Update the lookup plugin to force dep ordering

This change ensures that the dependency file ordering
for requirements file is kept intact for all fot the discovered
file used to build the repo environment.

Change-Id: I36d2044965c8a0809a417083c3f24c406b5a36c9
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

lookup/py_pkgs.py

@@ -40,10 +40,10 @@ ROLE_PACKAGES = dict()
 
 
 REQUIREMENTS_FILE_TYPES = [
-    'global-requirements.txt',
     'test-requirements.txt',
     'dev-requirements.txt',
     'requirements.txt',
+    'global-requirements.txt',
     'global-requirement-pins.txt'
 ]
 
@@ -296,7 +296,6 @@ class DependencyFileProcessor(object):
     @staticmethod
     def _filter_files(file_names, ext):
         """Filter the files and return a sorted list.
-
         :type file_names:
         :type ext: ``str`` or ``tuple``
         :returns: ``list``
@@ -513,8 +512,16 @@ class DependencyFileProcessor(object):
                             var_name=key
                         )
 
-        for file_name in self._filter_files(self.file_names, 'txt'):
-            if os.path.basename(file_name) in REQUIREMENTS_FILE_TYPES:
+        return_list = self._filter_files(self.file_names, 'txt')
+        for file_name in return_list:
+            base_name = os.path.basename(file_name)
+            if base_name in REQUIREMENTS_FILE_TYPES:
+                index = REQUIREMENTS_FILE_TYPES.index(base_name)
+                return_list.remove(file_name)
+                return_list.insert(index, file_name)
+        else:
+            print return_list
+            for file_name in return_list:
                 with open(file_name, 'r') as f:
                     packages = [
                         i.split()[0] for i in f.read().splitlines()

releasenotes/notes/force-dep-order-2c529683509e45da.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - The ``py_pkgs`` lookup plugin now has strict ordering for requirement files
+    discovered. These files are used to add additional requirements to the
+    python packages discovered. The order is defined by the constant,
+    ``REQUIREMENTS_FILE_TYPES`` which contains the following entries,
+    'test-requirements.txt', 'dev-requirements.txt', 'requirements.txt',
+    'global-requirements.txt', 'global-requirement-pins.txt'. The items in this
+    list are arranged from least to most priority.