veyron.io/tools: run hg in noninteractive mode
veyron.io/tools: run hg in noninteractive mode

Without this change, if ~/.hgrc is present but not configured to send
googlecode credentials, hg will wait for credentials on stdin. This blocks
the test process. After this change, the test will fail with "abort:
http authorization required".

Change-Id: I944e6dc59491e67ded4b644fb5b9deb0987d2d27

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools