CBG-5425 avoid writing zero sized files into sgcollect

[torcolvin]

CBG-5425 avoid writing zero sized files into sgcollect

When authentication fails some of the output for /debug/_pprof ends up 0 sized. These files aren't useful in sgcollect, and we know why a task failed in sync_gateway.log. I find this very confusing when looking at these files.

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

[Copilot]

Pull request overview

Adds an early-return in PythonTask.execute so that when the task callable returns a falsy value (e.g. b"" from a failed curl/auth-denied response in sgcollect's /debug/_pprof capture), no bytes are written to the destination file. Two new tests cover the empty-result path for both add_file_task and make_curl_task.

Changes:

• PythonTask.execute returns 0 immediately when self.callable() produces a falsy result, avoiding the subsequent result.encode() / fp.write(result) calls.
• Adds test_add_file_task_zero_size and test_make_curl_task_zero_size exercising the empty-result path.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tools/tasks.py	Skip writing/encoding when a PythonTask callable returns a falsy result.
tools-tests/tasks_test.py	New tests for the zero-size result handling in add_file_task and make_curl_task.