Make windows log_from_handle() handle partial lines
See legacy/trac#2045 (moved) for a full description of the problem. With legacy/trac#21654 (moved), we fixed the unix case, but the windows case may remain.
See legacy/trac#2045 (moved) for a full description of the problem. With legacy/trac#21654 (moved), we fixed the unix case, but the windows case may remain.