I'm seeing this exception during a build:
```
exception 'AphrontCharacterSetQueryException' with message 'Attempting to construct a query using a non-utf8 string when utf8 is expected. Use the `%B` conversion to escape binary strings data.' in /srv/phabricator/libphutil/src/aphront/storage/connection/mysql/AphrontBaseMySQLDatabaseConnection.php:331
Stack trace:
#0 /srv/phabricator/libphutil/src/aphront/storage/connection/mysql/AphrontMySQLiDatabaseConnection.php(10): AphrontBaseMySQLDatabaseConnection->validateUTF8String(' API.Funct...')
#1 /srv/phabricator/libphutil/src/xsprintf/qsprintf.php(170): AphrontMySQLiDatabaseConnection->escapeUTF8String(' API.Funct...')
#2 /srv/phabricator/libphutil/src/xsprintf/xsprintf.php(63): xsprintf_query(Object(AphrontMySQLiDatabaseConnection), 'UPDATE harborma...', 61, ' API.Funct...', 110)
#3 /srv/phabricator/libphutil/src/xsprintf/qsprintf.php(64): xsprintf('xsprintf_query', Object(AphrontMySQLiDatabaseConnection), Array)
#4 [internal function]: qsprintf(Object(AphrontMySQLiDatabaseConnection), 'UPDATE harborma...', ' API.Funct...', ' API.Funct...', '591772')
#5 /srv/phabricator/libphutil/src/xsprintf/queryfx.php(5): call_user_func_array('qsprintf', Array)
#6 /srv/phabricator/phabricator/src/applications/harbormaster/storage/build/HarbormasterBuildLog.php(140): queryfx(Object(AphrontMySQLiDatabaseConnection), 'UPDATE harborma...', ' API.Funct...', ' API.Funct...', '591772')
#7 /srv/phabricator/phabricator/src/applications/harbormaster/step/HarbormasterCommandBuildStepImplementation.php(98): HarbormasterBuildLog->append(' API.Funct...')
#8 /srv/phabricator/phabricator/src/applications/harbormaster/worker/HarbormasterTargetWorker.php(52): HarbormasterCommandBuildStepImplementation->execute(Object(HarbormasterBuild), Object(HarbormasterBuildTarget))
#9 /srv/phabricator/phabricator/src/infrastructure/daemon/workers/PhabricatorWorker.php(91): HarbormasterTargetWorker->doWork()
#10 /srv/phabricator/phabricator/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php(156): PhabricatorWorker->executeTask()
#11 /srv/phabricator/phabricator/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php(19): PhabricatorWorkerActiveTask->executeTask()
#12 /srv/phabricator/libphutil/src/daemon/PhutilDaemon.php(91): PhabricatorTaskmasterDaemon->run()
#13 /srv/phabricator/libphutil/scripts/daemon/exec/exec_daemon.php(111): PhutilDaemon->execute()
#14 {main}
```
I'm pretty sure utf8mb was supposed to fix this (and we are using utf8mb in our database), so I don't know what's going wrong.