otasigcheck: Don't fail a signature check if data will be wiped

If the --wipe_data command is being passed to recovery, skip the
signature check since the data will be wiped after the update is
installed

Change-Id: I6641f25abd044110faaf170ab2f7982460e77bcb

prebuilt/common/bin/otasigcheck.sh

@@ -3,6 +3,12 @@
 # Validate that the incoming OTA is compatible with an already-installed
 # system
 
+grep -q "Command:.*\"--wipe\_data\"" /tmp/recovery.log
+if [ $? -eq 0 ]; then
+  echo "Data will be wiped after install; skipping signature check..."
+  exit 0
+fi
+
 if [ -f /data/system/packages.xml -a -f /tmp/releasekey ]; then
   relCert=$(grep -A3 'package name="com.android.htmlviewer"' /data/system/packages.xml  | grep "cert index" | head -n 1 | sed -e 's|.*"\([[:digit:]][[:digit:]]*\)".*|\1|g')