[autotest] Reset needs to abide by _should_pending().

Currently, if Reset succeeds, it immediately forces the HQE into
Pending.  This breaks the ability to have multiple pre-job special
tasks.

BUG=None
DEPLOY=scheduler
TEST=Provision now runs

Change-Id: If59435bb0d3882fc643d2add3f268c49b3ce5224
Reviewed-on: https://gerrit.chromium.org/gerrit/61607
Reviewed-by: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
diff --git a/scheduler/monitor_db.py b/scheduler/monitor_db.py
index dd1ea49..1dc0799 100755
--- a/scheduler/monitor_db.py
+++ b/scheduler/monitor_db.py
@@ -1854,7 +1854,7 @@
             self.host.update_field('dirty', 0)
             self.host.set_status(models.Host.Status.READY)
 
-            if self.queue_entry:
+            if self._should_pending():
                 self.queue_entry.on_pending()