Scheduler: fix parallel-fetch order with --jobs=1

This avoids a case where the first prefetcher is discarded, causing
the second prefetcher to occupy the fetch queue before the first
fetcher has an opportunity to execute.

1 files changed, 7 insertions, 0 deletions

diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index d13e62266..6412d821d 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -752,6 +752,13 @@ class Scheduler(PollScheduler):
 					self._task_queues.fetch.add(prefetcher)
 					prefetchers[pkg] = prefetcher
 
+			# Start the first prefetcher immediately so that self._task()
+			# won't discard it. This avoids a case where the first
+			# prefetcher is discarded, causing the second prefetcher to
+			# occupy the fetch queue before the first fetcher has an
+			# opportunity to execute.
+			self._task_queues.fetch.schedule()
+
 	def _create_prefetcher(self, pkg):
 		"""
 		@return: a prefetcher, or None if not applicable