Specified as filter.apply, this is the callback that actually filters
data. If it successfully writes the output, it should return 0. Like
check, it can return git_error_code.GIT_PASSTHROUGH to indicate that the filter
doesn't want to run. Other error codes will stop filter processing and
return to the caller.
The payload value will refer to any payload that was set by the
check callback. It may be read from or written to as needed.
Callback to actually perform the data filtering
Specified as filter.apply, this is the callback that actually filters data. If it successfully writes the output, it should return 0. Like check, it can return git_error_code.GIT_PASSTHROUGH to indicate that the filter doesn't want to run. Other error codes will stop filter processing and return to the caller.
The payload value will refer to any payload that was set by the check callback. It may be read from or written to as needed.