Change update version checking when update_version is None

If a ChromiumOSUpdater instance is created with the
local_devserver=True option, the check_version_to_confirm_install()
method will always return False.  In the case of a local
devserver, we want to skip the version test, so this changes
the method to always return True for the local devserver case.

BUG=None
TEST=run_remote_tests with autoupdate/control.local

Change-Id: Ie0790e0e1498aaf8c60a2275829a4cbd35de454a
Reviewed-on: https://gerrit.chromium.org/gerrit/60151
Reviewed-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>
diff --git a/client/common_lib/cros/autoupdater.py b/client/common_lib/cros/autoupdater.py
index 9bce3d3..353605d 100644
--- a/client/common_lib/cros/autoupdater.py
+++ b/client/common_lib/cros/autoupdater.py
@@ -405,14 +405,16 @@
             autoupdater is trying to update to.
 
         """
+        # In the local_devserver case, we can't know the expected
+        # build, so just pass.
+        if not self.update_version:
+            return True
+
         # Always try the default check_version method first, this prevents
         # any backward compatibility issue.
         if self.check_version():
             return True
 
-        if not self.update_version:
-            return False
-
         # Remove R#- and -b# at the end of build version
         stripped_version = re.sub(r'(R\d+-|-b\d+)', '', self.update_version)