Revert "Revert "AU: do not copy filesystem during full updates""

This reverts commit d1cd325c3135d88498483da811b594ba6b91ce42

The problem that caused all autotests to fail with the original CL has now been rectified; lab devservers were updated to send the correct delta flag in their omaha response.

Change-Id: I664afb33f72856572baaa658cbd473c07271af36
Reviewed-on: https://gerrit.chromium.org/gerrit/56600
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/error_code.h b/error_code.h
index db023f7..aab0917 100644
--- a/error_code.h
+++ b/error_code.h
@@ -15,7 +15,7 @@
   kErrorCodeOmahaResponseHandlerError = 3,
   kErrorCodeFilesystemCopierError = 4,
   kErrorCodePostinstallRunnerError = 5,
-  kErrorCodeSetBootableFlagError = 6,  // TODO(petkov): Unused. Recycle?
+  kErrorCodePayloadMismatchedType = 6,
   kErrorCodeInstallDeviceOpenError = 7,
   kErrorCodeKernelDeviceOpenError = 8,
   kErrorCodeDownloadTransferError = 9,