Fetching compressed consensus gives it uncompressed if Accept-Encoding header is specified

This morning, we had this fun notice from doctor:

ERROR: Unable to retrieve the consensus from moria1 (http://128.31.0.39:9131/tor/status-vote/current/consensus.z): Error -3 while decompressing data: incorrect header check
ERROR: Unable to retrieve the vote from moria1 (http://128.31.0.39:9131/tor/status-vote/current/authority.z): Error -3 while decompressing data: incorrect header check

The file from that hour is available at http://seul.org/~arma/consensus-20170508.z.

The next weird thing is that using three different wget versions from different platforms, using

wget http://128.31.0.39:9131/tor/status-vote/current/consensus.z

to fetch a consensus from moria gives an uncompressed file. yawning and I can reproduce that, arma can not. Something fishy seems to be going on?