cros_chrome_sdk.py: Disallow colons in cache directory names

The directory is used in $PATH, so it must not contain a colon.

TEST=cros chrome-sdk --board link \
  --sdk-path gs://chromeos-image-archive/link-release/R37-5863.0.0
BUG=none

Change-Id: Ic62d4ed442d63a0e2261b33751a0a5de657bc889
Reviewed-on: https://chromium-review.googlesource.com/201464
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Tested-by: Michael Spang <spang@chromium.org>
1 file changed