Remove duplicate line in comment.
@@ -141,7 +141,6 @@ class RequirementPreparer(object):
# installation.
# FIXME: this won't upgrade when there's an existing
# package unpacked in `req.source_dir`
- # package unpacked in `req.source_dir`
if os.path.exists(os.path.join(req.source_dir, 'setup.py')):
raise PreviousBuildDirError(
"pip can't proceed with requirements '%s' due to a"
