tests/functional/asset: Fail assert fetch when retries are exceeded

Currently the fetch code does not fail gracefully when retry limit is
exceeded, it just falls through the loop with no file, which ends up
hitting other errors.

Add a check for non-existing file, which indicates the retry limit was
exceeded.

Reviewed-by: Daniel P. Berrangé <[email protected]>
Signed-off-by: Nicholas Piggin <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Thomas Huth <[email protected]>

Author: npiggin

tests/functional/qemu_test/asset.py

@@ -138,6 +138,9 @@ def fetch(self):
                 tmp_cache_file.unlink()
                 raise
 
+        if not os.path.exists(tmp_cache_file):
+            raise Exception("Retries exceeded downloading %s", self.url)
+
         try:
             # Set these just for informational purposes
             os.setxattr(str(tmp_cache_file), "user.qemu-asset-url",