Improve usefulness of HTTPStatus exceptions
Summary:
Some Phabricator errors produce a 500 response, which we curently render like this from Conduit:
$ arc diff --only Exception [HTTP/500] (Run with --trace for a full exception trace.) $
This is pretty worthless, and --trace does not help. Instead, show the first part of the body:
$ arc diff --only Exception [HTTP/500] Internal Server Error As received by the server, the request had a nonzero content length but no data. Normally this indicates that it exceeds the 'post_max_size' setting in the PHP configuration on the server. Increase the 'post_max_size' setting, or reduce the size of the request (request size according to 'Content-Length' was 518, 'post_max_size' is set to 256). (Run with --trace for a full exception trace.) $
Test Plan: See above.
Reviewers: vrana, btrahan
Reviewed By: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D3319