Invoke 'callback' for each entry in the given FETCH_HEAD file.
Return a non-zero value from the callback to stop the loop.
@param repo A repository object
@param callback Callback function
@param payload Pointer to callback data (optional)
@return 0 on success, non-zero callback return value, git_error_code.GIT_ENOTFOUND if
there is no FETCH_HEAD file, or other error code.
Invoke 'callback' for each entry in the given FETCH_HEAD file.
Return a non-zero value from the callback to stop the loop.
@param repo A repository object @param callback Callback function @param payload Pointer to callback data (optional) @return 0 on success, non-zero callback return value, git_error_code.GIT_ENOTFOUND if there is no FETCH_HEAD file, or other error code.