"this operation is only valid for push"

The sequence of calls

remote.ls_remotes(...)
remote.fetch(...)
remote.push(...)

works, while

remote.ls_remotes(...)
remote.push(...)

doesn't, producing the GIT_ERROR_NET / "this operation is only valid for push" error.

I think this is because ls_remotes() explicitly calls connect(..., GIT_DIRECTION_FETCH), and fetch() implicitly calls disconnect() (within git_remote_fetch()). If fetch() is not called between ls_remotes() and push(), git_remote_push() encounters an existing connection with FETCH direction, and returns an error (from git_smart__get_push_stream()).

This could be addressed in several ways: either by disconnecting explicitly in ls_remotes(), or maybe by changing the implementation of connect_or_reset_options() and the functions it calls to handle the case where direction is changing.

Start by reproducing the two call sequences using remote.ls_remotes(), remote.fetch(), and remote.push(), then inspect connect_or_reset_options() and the git_remote_push() path described in the issue. Done means pushing directly after ls_remotes() succeeds without the GIT_ERROR_NET error, with regression coverage for that sequence.