Cloning the dillo repository via HTTPS causes git not to print anything for a long time, it then works fine. In contrast, on GitHub it seems to start providing feedback immediately.

See thread on the mailing list.

Digging a bit into the git protocol, it seems we don't support git protocol version 2. This is what GitHub replies:

% curl -isS --user-agent 'git/2.30.2' -H 'Git-Protocol: version=2' \
    'https://github.com/dillo-browser/dillo/info/refs?service=git-upload-pack'
HTTP/2 200 
server: GitHub-Babel/3.0
content-type: application/x-git-upload-pack-advertisement
content-security-policy: default-src 'none'; sandbox
expires: Fri, 01 Jan 1980 00:00:00 GMT
pragma: no-cache
cache-control: no-cache, max-age=0, must-revalidate
vary: Accept-Encoding
date: Sun, 05 Oct 2025 23:06:58 GMT
x-frame-options: DENY
strict-transport-security: max-age=31536000; includeSubDomains; preload
x-github-request-id: D31C:4C38C:39FB37D:2C054F4:68E2FA11

001e# service=git-upload-pack
0000000eversion 2
0028agent=git/github-91d20c657fe1-Linux
0013ls-refs=unborn
0027fetch=shallow wait-for-done filter
0012server-option
0017object-format=sha1
0000

But this is what we reply:

% curl -isS --user-agent 'git/2.30.2' -H 'Git-Protocol: version=2' \
    'https://git.dillo-browser.org/dillo/info/refs?service=git-upload-pack' 
HTTP/1.1 200 OK
Server: nginx
Date: Sun, 05 Oct 2025 23:07:34 GMT
Content-Type: text/plain; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
Content-Disposition: inline; filename="info/refs"
Last-Modified: Sun, 05 Oct 2025 23:05:34 GMT
Expires: Sun, 05 Oct 2025 23:10:34 GMT
Strict-Transport-Security: max-age=31536000

f57e4fe95b2c0cfd2e966bcebdd6d21fd26e71bb        refs/heads/ci
29a46a2da7e9350a1252e30aea3c8294097f63a4        refs/heads/master
f48288b62f7e4d1e17cf06796d8738bd01de3746        refs/heads/mouse-back-forward
3b6ff743f6cd184740d5314409f729ff6ea57165        refs/notes/commits
...

The git documentation on protocol 2 states that a server will ignore the request if it doesn't support it:

https://git-scm.com/docs/gitprotocol-v2

When using the http:// or https:// transport a client makes a "smart" info/refs request as described in gitprotocol-http[5] and requests that v2 be used by supplying "version=2" in the Git-Protocol header.

Here is a patch that provides support for it.

https://git.oriole.systems/cgit/log/ui-clone.c?h=git-http-backend&showmsg=1&follow=1

https://lists.zx2c4.com/pipermail/cgit/2014-December/002312.html