It would be very helpful if you could specify the path to the private
key to use for ssh remotes just like in ssh.
git push origin master -i 'path_to_key'
Althought there are workarounds involving ssh config, if you have a
server that has hundreds of git repos, each with the own private key,
those workarounds become unusable.
This is a very popular request with thousands of comments about it, for example:
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