`soup_multipart_input_stream_next_part` never returns NULL when multipart termination is missing
According to the spec [1], the encapsulation boundary following the last body part requires two more hyphens at the end of the line:
--gc0p4Jq0M2Yt08jU534c0p--
And this is what libsoup expects. But if by some accident these two hyphens are missing we can get stuck in a loop:
- get new part
- read zero bytes
- repeat