update: fix bug when update tries to modify folder symlink In 1e4512eac59e0114bc60ecbcdc4157fc0fa0439d, I introduced a new bug: when a symlink points to a folder in commit A and to another folder in commit B, while updating from A to B, Mercurial will try to use removedir on this symlink, which will fail. This is a very bad bug, since it basically renders symlinks to folders unusable in repos. Added test case fails without a fix and passes with it.