Babel seems to autocreate a category sometimes, and to make the edit for that, it also needs to ensure its system user exists, which is also autocreated.
All this can be on GET from `api.php?action=parse`. And even in cases where an autocreation isn't needed (i.e. the system user already exists), `User::newSystemUser()` still opens a master connection.
```Expectation (masterConns <= 0) by ApiMain::setRequestExpectations not met:
[connect to 10.64.16.30 (metawiki)]
#0 /srv/mediawiki/php-1.29.0-wmf.6/includes/libs/rdbms/TransactionProfiler.php(160): TransactionProfiler->reportExpectationViolated()
#1 /srv/mediawiki/php-1.29.0-wmf.6/includes/libs/rdbms/loadbalancer/LoadBalancer.php(587): TransactionProfiler->recordConnection()
#2 /srv/mediawiki/php-1.29.0-wmf.6/includes/GlobalFunctions.php(3077): LoadBalancer->getConnection()
#3 /srv/mediawiki/php-1.29.0-wmf.6/includes/user/User.php(671): wfGetDB()
#4 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/BabelAutoCreate.class.php(96): User::newSystemUser()
#5 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/BabelAutoCreate.class.php(54): BabelAutoCreate::user()
#6 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/BabelBox/LanguageBabelBox.php(183): BabelAutoCreate::create()
#7 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/Babel.class.php(192): MediaWiki\Babel\BabelBox\LanguageBabelBox->getCategories()
#8 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/Babel.class.php(119): Babel::mGenerateContent()
#9 /srv/mediawiki/php-1.29.0-wmf.6/extensions/Babel/Babel.class.php(47): Babel::mGenerateContentTower()
#10 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(3379): Babel::Render()
#11 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(3103): Parser->callParserFunction()
#12 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Preprocessor_Hash.php(1015): Parser->braceSubstitution()
#13 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Preprocessor_Hash.php(1448): PPFrame_Hash->expand()
#14 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(3253): PPTemplateFrame_Hash->cachedExpand()
#15 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Preprocessor_Hash.php(1015): Parser->braceSubstitution()
#16 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(2917): PPFrame_Hash->expand()
#17 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(1265): Parser->replaceVariables()
#18 /srv/mediawiki/php-1.29.0-wmf.6/includes/parser/Parser.php(441): Parser->internalParse()
#19 /srv/mediawiki/php-1.29.0-wmf.6/includes/StubObject.php(113): Parser->parse()
#20 /srv/mediawiki/php-1.29.0-wmf.6/includes/StubObject.php(139): StubObject->_call()
#21 /srv/mediawiki/php-1.29.0-wmf.6/includes/content/WikitextContent.php(330): StubObject->__call()
#22 /srv/mediawiki/php-1.29.0-wmf.6/includes/content/AbstractContent.php(497): WikitextContent->fillParserOutput()
#23 /srv/mediawiki/php-1.29.0-wmf.6/includes/api/ApiParse.php(274): AbstractContent->getParserOutput()
#24 /srv/mediawiki/php-1.29.0-wmf.6/includes/api/ApiMain.php(1532): ApiParse->execute()
#25 /srv/mediawiki/php-1.29.0-wmf.6/includes/api/ApiMain.php(541): ApiMain->executeAction()
#26 /srv/mediawiki/php-1.29.0-wmf.6/includes/api/ApiMain.php(512): ApiMain->executeActionWithErrorHandling()
#27 /srv/mediawiki/php-1.29.0-wmf.6/api.php(83): ApiMain->execute()
#28 /srv/mediawiki/w/api.php(3): include()
#29 {main}```