Caused a regression breaking redirects to pages with '+' in the title.
Fixed in r25161 to match parser inline link behavior.
It looks like the fix made it so that leading colons will only be removed from links that contain a percent sign. This will break hard category redirects (which I realize have little value, but I've seen them around and it seems like a regression).
I don't see any regression testing something like #redirect [[:Category:Tests]].
The skipped ltrim() call looks unecessary to me; Title::newFromText() does this anyway (via the secureAndSplit(); it would only have a non-null effect if we passed a different default namespace into newFromText().).