Tweak multiplier in testing locks on CI.

Getting occasional random timeouts, rarely.

src/relstorage/tests/locking.py

@@ -285,10 +285,14 @@ def checkTL_OverlappedReadCurrent_SharedLocksFirst(self):
         assert self._storage._adapter.locker.supports_row_lock_nowait is not None
         if self._storage._adapter.locker.supports_row_lock_nowait:
             multiplier = 1.5
-            if RUNNING_ON_CI and 'mysql' in type(self).__name__:
-                # On Travis CI, we observe MySQL 8.0.21 to be very slow at this
-                # for some reason.
-                multiplier = 2.1
+            if RUNNING_ON_CI:
+                # Give some extra time on CI since the resources are shared
+                # and often extremely limited.
+                multiplier = 1.7
+                if 'mysql' in type(self).__name__:
+                    # On Travis CI, we observe MySQL 8.0.21 to be very slow at this
+                    # for some reason.
+                    multiplier = 2.1
             self.assertLessEqual(duration_blocking, commit_lock_timeout * multiplier)
         else:
             # Sigh. Old MySQL. Very slow. This takes around 4.5s to run both iterations.