_stream: Query the cache for elements as part of the pipeline

src/buildstream/_stream.py

@@ -416,14 +416,14 @@ def build(
 
         source_push_enabled = self._sourcecache.has_push_remotes()
 
-        # If source push is enabled, the source cache status of all elements
-        # is required, independent of whether the artifact is already available.
-        self.query_cache(elements, sources_of_cached_elements=source_push_enabled)
-
         # Now construct the queues
         #
         self._reset()
 
+        # If source push is enabled, the source cache status of all elements
+        # is required, independent of whether the artifact is already available.
+        self._add_queue(CacheQueryQueue(self._scheduler, sources_if_cached=source_push_enabled))
+
         if self._artifacts.has_fetch_remotes():
             self._add_queue(PullQueue(self._scheduler))
 

src/buildstream/_testing/runcli.py

@@ -231,7 +231,7 @@ def get_pulled_elements(self):
         return list(pulled)
 
     def get_discarded_elements(self):
-        discarded = re.findall(r"\[\s*(?:main|pull):(\S+)\s*\]\s*INFO\s*Discarded failed build", self.stderr)
+        discarded = re.findall(r"\[\s*(?:cache-query|pull):(\S+)\s*\]\s*INFO\s*Discarded failed build", self.stderr)
         if discarded is None:
             return []