v4.1.1 When no delimiter is found in a chunk, the chunk is reread.

[guyboertje]

Currently the read position is updated (to the end of the line) when a line is seen. A line here is the text before the delimiter.
When the delimiter is not seen in a chunk (can be simulated with a ridiculously low file_chunk_size) no lines are detected and the position is not updated. this means the seek position remains unchanged and the same chunk is repeatedly read.