ZeroDivisionError if source bundle smaller than 1mb

Hi,
I built a (GCP) DataFlow **** apache-beam (version 2.24.0) pipeline, using python.
The pipeline's stages are:
1. reading from BigQuery
2. running a custom function (using the ParDo while passing it a class inheriting 'beam.DoFn'), that transforms the read data.
3. writing the transformed data to BigQuery
 
The pipeline works fine when stage 1 is querying a small amount of data, but when it is querying data from the last six months (lots of data), I am getting this error:
 
```

apache_beam.runners.dataflow.dataflow_runner.DataflowRuntimeException: Dataflow pipeline failed. State:
FAILED, Error:
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/dataflow_worker/batchworker.py",
line 649, in do_work
    work_executor.execute()
  File "/usr/local/lib/python3.7/site-packages/dataflow_worker/executor.py",
line 179, in execute
    op.start()
  File "dataflow_worker/native_operations.py", line 38, in dataflow_worker.native_operations.NativeReadOperation.start
 
File "dataflow_worker/native_operations.py", line 39, in dataflow_worker.native_operations.NativeReadOperation.start
 
File "dataflow_worker/native_operations.py", line 44, in dataflow_worker.native_operations.NativeReadOperation.start
 
File "dataflow_worker/native_operations.py", line 48, in dataflow_worker.native_operations.NativeReadOperation.start
 
File "/usr/local/lib/python3.7/site-packages/dataflow_worker/workercustomsources.py", line 69, in _{_}iter{_}_
 
  self._source.start_position, self._source.stop_position)
  File "/usr/local/lib/python3.7/site-packages/apache_beam/io/concat_source.py",
line 78, in get_range_tracker
    start_position, stop_position, self._source_bundles)
  File "/usr/local/lib/python3.7/site-packages/apache_beam/io/concat_source.py",
line 131, in _{_}init{_}_
    self._compute_cumulative_weights(source_bundles[start[0]:last]) + [1]
*
  File "/usr/local/lib/python3.7/site-packages/apache_beam/io/concat_source.py", line 154, in _compute_cumulative_weights
 
  running_total.append(max(min_diff, min(1, running_total[-1] + w / total)))
ZeroDivisionError: float
division by zero

```

 
I saw this issue in your repository:
 
https://issues.apache.org/jira/browse/BEAM-10004
 
which is referencing the same problem I have, but even though this fix is already implemented in my version of apache-beam (2.24.0), I still get this error.
 
Can you please guide me in fixing this issue?
Is it something I am doing wrong or is this your bug?
 
Thank you in advance and have a good one!
 
Inbar Dekel

Imported from Jira [BEAM-13721](https://issues.apache.org/jira/browse/BEAM-13721). Original Jira may contain additional context.
Reported by: inbar.dekel.