xbuddy: remove unnecessary checks registering image paths

Allow registered images to be updated with new symlinks. The
symlinks are different for the same image when used inside and
outside chroot.

TEST=Run `cros flash` in and out of chroot using xbuddy directly

Change-Id: Idccad0636fab57edf77016573082ca0f9321cddd
Reviewed-on: https://chromium-review.googlesource.com/229650
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Yiming Chen <yimingc@chromium.org>
Commit-Queue: Yiming Chen <yimingc@chromium.org>
diff --git a/xbuddy.py b/xbuddy.py
index 6558bfb..b630c02 100644
--- a/xbuddy.py
+++ b/xbuddy.py
@@ -566,12 +566,6 @@
       build_ids.extend(['/'.join([b, v]) for v
                         in os.listdir(board_dir) if not v == LATEST])
-    # Check currently registered images.
-    for f in os.listdir(self._timestamp_folder):
-      build_id = Timestamp.TimestampToBuild(f)
-      if build_id in build_ids:
-        build_ids.remove(build_id)
     # Symlink undiscovered images, and update timestamps if manage_builds is on.
     for build_id in build_ids:
       link = os.path.join(self.static_dir, build_id)