attempt to stop using pip internals

This should let us stop using pip internals, which breaks us all the
time.

Conflicts:
	update.py

Change-Id: I10ada6860768017d4eb3c729f2870f2c7f4a46d7
(cherry picked from commit 166a9f1d50)

update.py

@@ -31,7 +31,7 @@ import os
 import os.path
 import sys
 
-from pip import req
+import pkg_resources
 
 VERBOSE = None
 
@@ -67,7 +67,6 @@ setuptools.setup(
     pbr=True)
 """
 
-
 # A header for the requirements file(s).
 _REQS_HEADER = [
     '# The order of packages is significant, because pip processes '
@@ -93,17 +92,14 @@ class Change(object):
         return "%-30.30s ->   %s" % (self.old, self.new)
 
 
-def _parse_pip(pip):
+def _package_name(pip_line):
+    """Return normalized (lower case) package name.
 
-    install_require = req.InstallRequirement.from_line(pip)
-    if install_require.editable:
-        return pip
-    elif hasattr(install_require, "url") and install_require.url:
-        return pip
-    elif hasattr(install_require, "link") and install_require.link:
-        return pip
-    else:
-        return install_require.req.key
+    This is needed for comparing old and new dictionaries of
+    requirements to ensure they match.
+    """
+    name = pkg_resources.Requirement.parse(pip_line).project_name
+    return name.lower()
 
 
 def _pass_through(pip):
@@ -115,9 +111,7 @@ def _pass_through(pip):
 
 
 def _functionally_equal(old_requirement, new_requirement):
-    old_require = req.InstallRequirement.from_line(old_requirement)
-    new_require = req.InstallRequirement.from_line(new_requirement)
-    return old_require.req == new_require.req
+    return old_requirement == new_requirement
 
 
 def _read(filename):
@@ -139,7 +133,7 @@ def _parse_reqs(filename):
         pip = pip.strip()
         if _pass_through(pip):
             continue
-        reqs[_parse_pip(pip)] = pip
+        reqs[_package_name(pip)] = pip
     return reqs
 
 
@@ -167,7 +161,7 @@ def _sync_requirements_file(source_reqs, dev_reqs, dest_path,
                 new_reqs.write(old_line)
                 continue
 
-            old_pip = _parse_pip(old_require.lower())
+            old_pip = _package_name(old_require)
 
             # Special cases:
             # projects need to align hacking version on their own time
@@ -177,8 +171,8 @@ def _sync_requirements_file(source_reqs, dev_reqs, dest_path,
 
             if old_pip in source_reqs:
                 # allow it to be in dev-requirements
-                if ((old_pip in dev_reqs) and (old_require.lower() ==
-                                               dev_reqs[old_pip])):
+                if ((old_pip in dev_reqs) and (
+                        old_require == dev_reqs[old_pip])):
                     new_reqs.write("%s\n" % dev_reqs[old_pip])
                 elif _functionally_equal(old_require, source_reqs[old_pip]):
                     new_reqs.write(old_line)