Ref T13217. See https://discourse.phabricator-community.org/t/unsafe-raw-string-warnings-while-importing-git-commits/2191.
Hunt down and fix two more qsprintf() things.
I just converted the "performance optimization" into a normal, safe call since we're dealing with far less SVN stuff nowadays and the actual issue has been lost in the mists of time. If it resurfaces, we can take another look.