cr50_utils: add -b hack to work with broken usb_updater

For a time usb_updater was broken. Running 'usb_updater -b $IMG' wont
work on chromeos images built with that image. There is a simple
workaround. 'usb_updater -b $IMG $IMG' will run successfully. This
change modifies cr50_utils.GetBinVersion to run 'usb_updater -b $IMG
$IMG'. This command works on all usb_updater versions.

BUG=b:37958867
TEST=none
BRANCH=none

Change-Id: I5d38cbcebcd5805ed98a7c3523c7418381290e69
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/493614
Reviewed-by: Wai-Hong Tam <waihong@google.com>
diff --git a/client/common_lib/cros/cr50_utils.py b/client/common_lib/cros/cr50_utils.py
index 00b1534..b2b7337 100644
--- a/client/common_lib/cros/cr50_utils.py
+++ b/client/common_lib/cros/cr50_utils.py
@@ -126,7 +126,9 @@
 
 def GetBinVersion(client, image=CR50_FILE):
     """Get the image version using 'usb_updater --binver image'"""
-    return GetVersionFromUpdater(client, ["--binver", image])
+    # TODO(mruthven) b/37958867: change to ["--binver", image] when usb_updater
+    # is fixed
+    return GetVersionFromUpdater(client, ["--binver", image, image])
 
 
 def GetVersionString(ver):