Correctly parse old ImageInfo command line arguments.

Parsing of source image_info command line arguments was incorrectly
hidden behind a short circuit boolean expression. This prevented
them from ever being present.

BUG=chromium:258634
TEST=cros_generate_paylaod <...> && paycheck -D

Change-Id: Ieb22f2056cf8e30edb4ae2c990301b6f30ed2403
Reviewed-on: https://chromium-review.googlesource.com/174582
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
diff --git a/delta_diff_generator.cc b/delta_diff_generator.cc
index 48fe177..2df0de9 100644
--- a/delta_diff_generator.cc
+++ b/delta_diff_generator.cc
@@ -1405,7 +1405,7 @@
     LOG_IF(WARNING, old_image_block_count != new_image_block_count)
         << "Old and new images have different block counts.";
 
-    // If new_image_info is present, old_image_info must but be present.
+    // If new_image_info is present, old_image_info must be present.
     TEST_AND_RETURN_FALSE((bool)old_image_info == (bool)new_image_info);
   } else {
     // old_image_info must not be present for a full update.