libgit2 seems to hang when cloning a URL that has a redirect with an empty body.

Reproduction steps

Try to clone the URL https://gitlab.com/ehuss/test

Expected behavior

Should be able to clone with a redirect.

Actual behavior

libgit2 hangs when cloning that URL. From my investigation, this is roughly what I see:

1. gitlab responds to the initial request with a redirect to https://gitlab.com/ehuss/test.git/info/refs?service=git-upload-pack
   • Notice that it added .git to the URL
   • That response has a Content-Type: text/html; charset=utf-8 header and Content-Length: 0
2. on_headers_complete detects the Content-Type header and sets client->state to READING_BODY
3. The loop in http_stream_read goes again, generating a new request with the new URL
4. git_http_client_send_request is called, and at the very top it detects READING_BODY and calls complete_response_body which tries to read more data from the server, but this hangs indefinitely since there is no body coming.

I'm not familiar enough with this code to make a real suggestion (maybe it should check for content_length==0 somewhere? or maybe it shouldn't set READING_BODY if content_length==0?).

Version of libgit2 (release number or SHA1)

21a351b

Operating system(s) tested

Any