Add VersionlessRequirement adapter to suppress the version number in a Distribution. Ref #439.

setuptools/command/develop.py

@@ -167,3 +167,26 @@ class develop(easy_install):
             script_text = f.read()
             f.close()
             self.install_script(dist, script_name, script_text, script_path)
+
+
+class VersionlessRequirement(object):
+    """
+    Adapt a pkg_resources.Distribution to simply return the project
+    name as the 'requirement' so that scripts will work across
+    multiple versions.
+
+    >>> dist = Distribution(project_name='foo', version='1.0')
+    >>> str(dist.as_requirement())
+    'foo==1.0'
+    >>> adapted_dist = VersionlessRequirement(dist)
+    >>> str(adapted_dist.as_requirement())
+    'foo'
+    """
+    def __init__(self, dist):
+        self.__dist = dist
+
+    def __getattr__(self, name):
+        return getattr(self.__dist, name)
+
+    def as_requirement(self):
+        return self.project_name