At first, I had a similar issue that I tried to solve with this post. Then after downloading the latest git client and latest git credential manager I still have this following error :
fatal: the remote end hung up unexpectedly
fatal: the remote end hung up unexpectedly
fatal: the remote end hung up unexpectedly
Pushing to https://myLogin@bitbucket.org/myLogin/myPorject.git
error: failed to push some refs to 'https://myLogin@bitbucket.org/myLogin/myProject.git'
The only step I did not know how to proceed is changing the sourceTree. Where is the "Tools" to do "Tools > Options > Git " and click "Use System Git version"

Unless it is another problem that I have?
Thank you for your help