Merge branch 'pg-tests-fix' of github.com:asthamohta/python-spanner into pg-tests-fix

Author: asthamohta

tests/system/_helpers.py

@@ -31,7 +31,7 @@
 INSTANCE_ID = os.environ.get(INSTANCE_ID_ENVVAR, INSTANCE_ID_DEFAULT)
 
 SKIP_BACKUP_TESTS_ENVVAR = "SKIP_BACKUP_TESTS"
-SKIP_BACKUP_TESTS = True  # os.getenv(SKIP_BACKUP_TESTS_ENVVAR) == True
+SKIP_BACKUP_TESTS = os.getenv(SKIP_BACKUP_TESTS_ENVVAR) is not None
 
 INSTANCE_OPERATION_TIMEOUT_IN_SECONDS = int(
     os.getenv("SPANNER_INSTANCE_OPERATION_TIMEOUT_IN_SECONDS", 560)