Don't store temporary image in image dir.

Storing temporary images in the same dir as other images causes problems
for the archive stage, as this command grabs all images in the directory.
This includes temporary files which might disappear while zip is
working.

BUG=chromium:235053
TEST=cbuildbot run

Change-Id: I4dac10050931d273ca7b2860eab937b109ae1781
Reviewed-on: https://gerrit.chromium.org/gerrit/49059
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
1 file changed