roll_util: Change "Fixes:" to "Original-Fixes:"

Change-Id: I8723a652ebe0a686804fb76b5d442b87161d0d2a
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/27780
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
diff --git a/recipe_modules/roll_util/api.py b/recipe_modules/roll_util/api.py
index f75ec4d..9252686 100644
--- a/recipe_modules/roll_util/api.py
+++ b/recipe_modules/roll_util/api.py
@@ -26,6 +26,7 @@
 ESCAPE_TAGS = [
     'Bug:',
     'Fixed:',
+    'Fixes:',
     'Requires:',
     'Reviewed-on:',
 ]