bin/doins.py: remove file before creating symlink (bug 640376)

Fixes: d9522ba661b5 ("Rewrite doins in python (bug 624526)")
Bug: https://bugs.gentoo.org/640376
(cherry picked from commit 992b4ffdcbf469db543c9cab90a5f7a3a4125c97)

BUG=chromium:712659
TEST=precq passes

Change-Id: I2f3361aeaeed16e1c857881e25bf12c9c3f8eb91
Reviewed-on: https://chromium-review.googlesource.com/820199
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
1 file changed