--hex-blob isn't used, mysqldump produces
  INSERT VALUES('cryptic chars');
and when this dump is later used for restoring, the string is treated
as utf8 (per the "SET NAMES utf8" in the dump) and Server warns
if the chars are not utf8 (after the fix for Bug#20238729); but this warning
is wrong, as data isn't meant to be utf8. It scares users
when they restore data (fortunately the data is properly inserted).
Fix: make mysqldump declare that it's not meant to be utf8:
add "_binary" in front of the string in the dump.
Also fixing mysqlPump which had same bug.