Pass 'user_project' if set for blob downloads w/ 'mediaLink' set

storage/google/cloud/storage/blob.py

@@ -35,7 +35,11 @@
 import warnings
 
 import httplib2
+from six.moves.urllib.parse import parse_qsl
 from six.moves.urllib.parse import quote
+from six.moves.urllib.parse import urlencode
+from six.moves.urllib.parse import urlsplit
+from six.moves.urllib.parse import urlunsplit
 
 import google.auth.transport.requests
 from google import resumable_media
@@ -404,14 +408,22 @@ def _get_download_url(self):
         :returns: The download URL for the current blob.
         """
         if self.media_link is None:
-            download_url = _DOWNLOAD_URL_TEMPLATE.format(path=self.path)
+            base_url = _DOWNLOAD_URL_TEMPLATE.format(path=self.path)
+            scheme, netloc, path, query, frag = urlsplit(base_url)
+            query = parse_qsl(query)
+            # Only add `generation' for synthesized URLs: 'mediaLink' from
+            # server presumably already encodes it.
             if self.generation is not None:
-                download_url += u'&generation={:d}'.format(self.generation)
-            if self.user_project is not None:
-                download_url += u'&userProject={}'.format(self.user_project)
-            return download_url
+                query.append(('generation', '{:d}'.format(self.generation)))
         else:
-            return self.media_link
+            scheme, netloc, path, query, frag = urlsplit(self.media_link)
+            query = parse_qsl(query)
+
+        if self.user_project is not None:
+            query.append(('userProject', self.user_project))
+
+        query = urlencode(query)
+        return urlunsplit((scheme, netloc, path, query, frag))
 
     def _do_download(self, transport, file_obj, download_url, headers):
         """Perform a download without any error handling.

storage/tests/unit/test_blob.py

@@ -366,7 +366,7 @@ def test__make_transport(self, fake_session_factory):
 
     def test__get_download_url_with_media_link(self):
         blob_name = 'something.txt'
-        bucket = mock.Mock(spec=[])
+        bucket = _Bucket(name='IRRELEVANT')
         blob = self._make_one(blob_name, bucket=bucket)
         media_link = 'http://test.invalid'
         # Set the media link on the blob
@@ -375,6 +375,19 @@ def test__get_download_url_with_media_link(self):
         download_url = blob._get_download_url()
         self.assertEqual(download_url, media_link)
 
+    def test__get_download_url_with_media_link_w_user_project(self):
+        blob_name = 'something.txt'
+        user_project = 'user-project-123'
+        bucket = _Bucket(name='IRRELEVANT', user_project=user_project)
+        blob = self._make_one(blob_name, bucket=bucket)
+        media_link = 'http://test.invalid'
+        # Set the media link on the blob
+        blob._properties['mediaLink'] = media_link
+
+        download_url = blob._get_download_url()
+        self.assertEqual(
+            download_url, '{}?userProject={}'.format(media_link, user_project))
+
     def test__get_download_url_on_the_fly(self):
         blob_name = 'bzzz-fly.txt'
         bucket = _Bucket(name='buhkit')