Cryptic error message from querier

[bboreham]

Example:

level=warn ts=2021-03-05T09:08:41.326358339Z caller=logging.go:71 traceID=44b1364b1ae4070a msg="POST /api/prom/api/v1/query (500) 1.767165ms Response:
\"\\x1f\\x8b\\b\\x00\\x00\\x00\\x00\\x00\\x00\\xff4\\xcaщ\\xc3@\\fE\\xd1V\\x1e\\xfa\\xde\\n\\\\\\xc76\\xa0\\xb5\\x1e\\x1b
\\x91\\xb1ƌd<!\\xa4\\xf7\\x90\\x84|]\\xb8\\x9c\\xbbdi\\x1d)\\x8bp\\x8c>\\xe4\\xe7\\xd3\\xdf\\xdbNYģ8B\\xdbw\\xbf\\xd8
\\xdc5\\xcc\\xe3\\x1f\\xc9\\xe1\\xcc\\x05\\u007f\\xc7ze\\xc1\\xc38\\xe1\\x89\\xea\\x1d\\xbd\\x194\\fu!\\x9af\\xa1|#\\xbcpj
\\xe2\\xd8M\\x8b\\x06Ε\\xb4|#m\\xad\\x9f4l:\\x91\\xa5\\x8d\\xc1Ly<\\x01\\x00\\x00\\xff\\xff\\x01\\x00\\x00\\xff\\xff+qK\\xf3
\\xa0\\x00\\x00\\x00\" ws: false; Accept-Encoding: gzip; Content-Length: 79; Content-Type: application/x-www-form-urlencoded; Uber-Trace-Id: 44b1364b1ae4070a:546ec3224da98134:19c22448f0ee38f5:0; User-Agent: Go-http-client/1.1; X-Scope-Orgid: 2; uber-trace-id: 44b1364b1ae4070a:462ea9b07da3c33f:546ec3224da98134:0; "

The most obvious thing is that the error message is in hex.
Reporting it as coming from logging.go:71 is also pretty useless.
Reporting the trace ID three times is irritating, but perhaps harder to fix.

Similar to #938
Guessing this problem might originate in https://github.com/weaveworks/common.

[Tristan971]

Seems to be back here too, a quick googling suggests this is in fact a gzip blob