Update Flask code with new code generated by Swagger
Yeah, there isn't really a good workflow for that yet AFAICS.
One thing you can do is check the original generated code into git on a branch called "generated" or similar. Then merge that to master and start working on it. If, at a later point, you extend your swagger definition, you can generate the code again, switch to the generated branch, overwrite the existing code with the newly generated code, commit and merge to master again. If all you had were some additional endpoints, this should even work without any merge conflicts.
It would of course be nicer if the swagger tools had a concept of which code they generated and be able to update generated code, but until then this should be a bearable workaround.