Update code to use a std. read_requirements_file()

Change-Id: I48c26cc432a0322c5482bc1645537f59c1f6717d

openstack_requirements/cmds/build_lower_constraints.py

@@ -18,18 +18,13 @@
 import argparse
 import collections
 
-from openstack_requirements import requirement
+from openstack_requirements.utils import read_requirements_file
+
 
 import packaging.specifiers
 import packaging.version
 
 
-def read_requirements_file(filename):
-    with open(filename, 'rt') as f:
-        body = f.read()
-    return requirement.parse(body)
-
-
 def get_requirements_version(req):
     """Find the version for a requirement.
 

openstack_requirements/cmds/check_conflicts.py

@@ -20,13 +20,7 @@ import traceback
 
 import pkg_resources
 
-from openstack_requirements import requirement
-
-
-def read_requirements_file(filename):
-    with open(filename, 'rt') as f:
-        body = f.read()
-    return requirement.parse(body)
+from openstack_requirements.utils import read_requirements_file
 
 
 def main():

openstack_requirements/cmds/check_exists.py

@@ -22,12 +22,7 @@ from packaging.version import Version
 
 from openstack_requirements import project
 from openstack_requirements import requirement
-
-
-def read_requirements_file(filename):
-    with open(filename, 'rt') as f:
-        body = f.read()
-    return requirement.parse(body)
+from openstack_requirements.utils import read_requirements_file
 
 
 def main(args=None):

openstack_requirements/cmds/validate.py

@@ -19,12 +19,7 @@ import os
 
 from openstack_requirements import constraints
 from openstack_requirements import requirement
-
-
-def read_requirements_file(filename):
-    with open(filename, 'rt') as f:
-        body = f.read()
-    return requirement.parse(body)
+from openstack_requirements.utils import read_requirements_file
 
 
 def main():

openstack_requirements/utils.py

@@ -0,0 +1,7 @@
+from openstack_requirements import requirement
+
+
+def read_requirements_file(filename):
+    with open(filename, 'rt') as f:
+        body = f.read()
+    return requirement.parse(body)