localrepo: remove unneeded os.unlink call in wwrite The opener already unlinks the filename before 'w'riting, for both the symlink and the normal file case. It also now resets the flags for normal files on 'w'rite, which makes this os.unlink call completely redundant. For Windows, removing this extra unlink call helps to avoid tripping issue2524 (os.unlink followed by a write).