Make sure 'NAME @ URL' actually resembles a URL

This prevents "pseudo URL" VCS requirements from going through the
parser and cause issues later.

Author: uranusjr

src/pip/_internal/req/constructors.py

@@ -81,7 +81,7 @@ def parse_editable(editable_req):
     except InvalidRequirement:
         pass
     else:
-        if req.url:
+        if req.url and "://" in req.url:
             # Join the marker back into the name part. This will be parsed out
             # later into a Requirement again.
             if req.marker: