feat(tests): only try connecting to VPN once

tests/ui_tests/reporting/download.py

@@ -11,8 +11,15 @@ RECORDS_WEBSITE = "https://firmware.corp.sldev.cz/ui_tests/"
 FIXTURES_MASTER = "https://raw.githubusercontent.com/trezor/trezor-firmware/master/tests/ui_tests/fixtures.json"
 FIXTURES_CURRENT = pathlib.Path(__file__).parent / "../fixtures.json"
 
+_dns_failed = False
+
 
 def fetch_recorded(hash, path):
+    global _dns_failed
+
+    if _dns_failed:
+        raise RuntimeError("Not trying firmware.corp.sldev.cz again after DNS failure.")
+
     zip_src = RECORDS_WEBSITE + hash + ".zip"
     zip_dest = path / "recorded.zip"
 
@@ -21,6 +28,7 @@ def fetch_recorded(hash, path):
     except urllib.error.HTTPError:
         raise RuntimeError("No such recorded collection was found on '%s'." % zip_src)
     except urllib.error.URLError:
+        _dns_failed = True
         raise RuntimeError(
             "Server firmware.corp.sldev.cz could not be found. Are you on VPN?"
         )