The go http library will normally implicitly set an Accept-Encoding of
gzip to requests and then transparently decompress the response body.
However, if the Accept-Encoding header is explicitly set by the caller
it will no longer transparently decompress the body. This was causing
HTTP LLB sources to have unexpectedly compressed contents.
The fix here just unsets the Accept-Encoding header after the HEAD
request. Another possible fix would be to do our own gzip decompression
after reading the body if it was gzipped, but this approach seemed
slightly simpler.
Signed-off-by: Erik Sipsma <erik@sipsma.dev>
Tonis Tiigi