patch 8.0.0105
Problem:    When using ch_read() with zero timeout, can't tell the difference
            between reading an empty line and nothing available.
Solution:   Add ch_canread().
diff --git a/src/proto/channel.pro b/src/proto/channel.pro
index 8640fa7..f127268 100644
--- a/src/proto/channel.pro
+++ b/src/proto/channel.pro
@@ -25,6 +25,7 @@
 int channel_collapse(channel_T *channel, ch_part_T part, int want_nl);
 int channel_can_write_to(channel_T *channel);
 int channel_is_open(channel_T *channel);
+int channel_has_readahead(channel_T *channel, ch_part_T part);
 char *channel_status(channel_T *channel, int req_part);
 void channel_info(channel_T *channel, dict_T *dict);
 void channel_close(channel_T *channel, int invoke_close_cb);