Set CROS.sharding_factory to 1 and set an override in the BVT suite.

When running out of band tests, initially, only allow them to shard to
1 DUT per board. This behavior will be adjusted overtime based on how long
a SUITE run takes and the need for the information.

TEST=None
BUG=None

Change-Id: I0eb0152ba3b14306e47c6419fe1f6644ddeb0b02
Reviewed-on: https://gerrit.chromium.org/gerrit/20381
Reviewed-by: Chris Masone <cmasone@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Tested-by: Scott Zawalski <scottz@chromium.org>
Commit-Ready: Scott Zawalski <scottz@chromium.org>
diff --git a/test_suites/control.bvt b/test_suites/control.bvt
index 1ede42d..f844277 100755
--- a/test_suites/control.bvt
+++ b/test_suites/control.bvt
@@ -13,13 +13,16 @@
 TEST_TYPE = "Server"
 
 DOC = """
-This is the Build Verification Test suite.  It should consist of SHORT tests
+This is the Build Verification Test suite. It should consist of SHORT tests
 that validate critical functionality -- ability to acquire connectivity, perform
 crash reporting, get updates, and allow a user to log in, among other things.
+This suite sets num to 4 in the reimage_and_run call to make sure we run
+across 4 different machines. This overrides the CROS.sharding_factor option in
+the global_config.
 
 @param build: The name of the image to test.
               Ex: x86-mario-release/R17-1412.33.0-a1-b29
-@param board: The board to test on.  Ex: x86-mario
+@param board: The board to test on. Ex: x86-mario
 @param pool: The pool of machines to utilize for scheduling. If pool=None
              board is used.
 @param check_hosts: require appropriate live hosts to exist in the lab.
@@ -31,5 +34,5 @@
 
 dynamic_suite.reimage_and_run(
     build=build, board=board, name='bvt', job=job, pool=pool,
-    check_hosts=check_hosts, add_experimental=True,
+    check_hosts=check_hosts, add_experimental=True, num=4,
     skip_reimage=dynamic_suite.skip_reimage(globals()))