storage test run live results in different recording in different python environments

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-`test_storage_blob_incremental_copy` results in a different recording when run in Python2 vs Python3
-the python3 recording fails when played back in python2

### Environment summary

Install Method (e.g. pip, interactive script, apt-get, Docker, MSI, edge build) / CLI version (`az --version`) / OS version / Shell Type (e.g. bash, cmd.exe, Bash on Windows)

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Start by locating the test_storage_blob_incremental_copy test and the recording/playback utilities it uses. Run the test under Python 2 and Python 3, then compare the generated recordings and playback results. Done means both environments produce compatible recordings and the Python 3 recording can be replayed in Python 2.

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