Already exists -- race condition
Backtrace:
#0 /usr/local/apache/common-local/wmf-deployment/extensions/CentralAuth/SpecialMergeAccount.php(64): SpecialMergeAccount->doInitialMerge()
#1 /usr/local/apache/common-local/wmf-deployment/includes/SpecialPage.php(559): SpecialMergeAccount->execute(NULL)
#2 /usr/local/apache/common-local/wmf-deployment/includes/Wiki.php(242): SpecialPage::executePath(Object(Title))
#3 /usr/local/apache/common-local/wmf-deployment/includes/Wiki.php(64): MediaWiki->handleSpecialCases(Object(Title), Object(OutputPage), Object(WebRequest))
#4 /usr/local/apache/common-local/wmf-deployment/index.php(117): MediaWiki->performRequestForTitle(Object(Title), NULL, Object(OutputPage), Object(User), Object(WebRequest))
#5 /usr/local/apache/common-local/live-1.5/index.php(3): require('/usr/local/apac...')
#6 {main}