Handle already running flow for the same user

[etshi]

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• Errbot version: 9.9.9
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• Python version: 3.6
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Issue description

When in the middle of a flow with auto triggered first_step, if I used the command that triggered the first step. The first step still reruns.
My question is How can I check if a flow from the same user is already running, so I can end it in the above case?

Steps to reproduce

Flow:
!step_one !steptwo End

step_one is auto triggered and depending on the input from user either end or move to step_two. on step_one just use the same command that triggers step_one again

Additional info