Ignore empty PULL_NUMBER environment variables in SDK tests (kubeflow#11714)

On pushes to the master branch, PULL_NUMBER was an empty string.

Signed-off-by: mprahl <[email protected]>
(cherry picked from commit a7ec34f)

Author: mprahl

test/kfp-kubernetes-execution-tests/sdk_execution_tests.py

@@ -111,7 +111,7 @@ def run(test_case: TestCase) -> Tuple[str, client.client.RunPipelineResult]:
 
 def get_kfp_package_path() -> str:
     repo_name = os.environ.get('REPO_NAME', 'kubeflow/pipelines')
-    if os.environ.get('PULL_NUMBER') is not None:
+    if os.environ.get('PULL_NUMBER'):
         path = f'git+https://github.com/{repo_name}.git@refs/pull/{os.environ["PULL_NUMBER"]}/merge#subdirectory=sdk/python'
     else:
         path = f'git+https://github.com/{repo_name}.git@master#subdirectory=sdk/python'

test/sdk-execution-tests/sdk_execution_tests.py

@@ -100,7 +100,7 @@ def run(test_case: TestCase) -> Tuple[str, client.client.RunPipelineResult]:
 
 def get_kfp_package_path() -> str:
     repo_name = os.environ.get('REPO_NAME', 'kubeflow/pipelines')
-    if os.environ.get('PULL_NUMBER') is not None:
+    if os.environ.get('PULL_NUMBER'):
         path = f'git+https://github.com/{repo_name}.git@refs/pull/{os.environ["PULL_NUMBER"]}/merge#subdirectory=sdk/python'
     else:
         path = f'git+https://github.com/{repo_name}.git@master#subdirectory=sdk/python'