new core.runner helper to avoid local caching issues w. coverage tests; .settings, apps.dash.tests.ITs.test_wallet_views updated accordingly

src/core/runner.py

@@ -0,0 +1,15 @@
+import time
+from django.test.runner import DiscoverRunner
+
+
+class RobustCompressorTestRunner(DiscoverRunner):
+    def setup_test_environment(self, **kwargs):
+        super().setup_test_environment(**kwargs)
+        from compressor.storage import CompressorFileStorage
+        _orig_save = CompressorFileStorage.save
+        def _robust_save(self, name, content):
+            for _ in range(5):
+                try: return _orig_save(self, name, content)
+                except PermissionError: time.sleep(0.05)
+            raise
+        CompressorFileStorage.save = _robust_save