Workaround for broken 'ps' command on M.

Change-Id: Ifabc6bb2b0e3780306e8a3ad45531c50c7627ed1
diff --git a/tools/setup-buildbot-device.sh b/tools/setup-buildbot-device.sh
index 9e085b5..1e9c763 100755
--- a/tools/setup-buildbot-device.sh
+++ b/tools/setup-buildbot-device.sh
@@ -46,5 +46,13 @@
 adb logcat -p
 
 echo -e "${green}Kill stalled dalvikvm processes${nc}"
-processes=$(adb shell "ps" | grep dalvikvm | awk '{print $2}')
-for i in $processes; do adb shell kill -9 $i; done
+# 'ps' on M can sometimes hang.
+timeout 2s adb shell "ps"
+if [ $? = 124 ]; then
+  echo -e "${green}Rebooting device to fix 'ps'${nc}"
+  adb reboot
+  adb wait-for-device root
+else
+  processes=$(adb shell "ps" | grep dalvikvm | awk '{print $2}')
+  for i in $processes; do adb shell kill -9 $i; done
+fi