Reported by Timonator on irc:

pg_query() [function.pg-query]: Query failed:
ERROR: invalid byte sequence for encoding "UTF8": 0x9a
HINT: This error can also happen if the byte sequence does not
match the encoding expected by the server, which is controlled
by "client_encoding". in ./includes/DatabasePostgres.php on line 389

A database error has occurred Query: SELECT
math_outputhash,math_html_conservativeness,math_html,math_mathml FROM math WHERE
math_inputhash = '\x06zfsq`X��y���.�V ' LIMIT 1 Function: MathRenderer::_recall
Error: 1 ERROR: invalid byte sequence for encoding "UTF8": 0x9a HINT: This error
can also happen if the byte sequence does not match the encoding expected by the
server, which is controlled by "client_encodin

This is caused by pack() used to store the md5 hash as a binary field
in the database.

Version: 1.10.x
Severity: major