Use diff.ignoreSubmodules=all when committing patches.

Bug:1486973
Recipe-Nontrivial-Roll: build
Change-Id: Ifde97d61d55e7f78068bc2f745ec0816bbb5d694
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4909801
Commit-Queue: Joanna Wang <jojwang@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

recipes/README.recipes.md

@@ -791,7 +791,7 @@ Raises:
 
 Returns a presubmit step.
 
-— **def [execute](/recipes/recipe_modules/presubmit/api.py#101)(self, bot_update_step, skip_owners=False, run_all=False):**
+— **def [execute](/recipes/recipe_modules/presubmit/api.py#103)(self, bot_update_step, skip_owners=False, run_all=False):**
 
 Runs presubmit and sets summary markdown if applicable.
 

recipes/recipe_modules/presubmit/api.py

@@ -85,6 +85,8 @@ class PresubmitApi(recipe_api.RecipeApi):
                    'user.email=commit-bot@chromium.org',
                    '-c',
                    'user.name=The Commit Bot',
+                   '-c',
+                   'diff.ignoreSubmodules=all',
                    'commit',
                    '-a',
                    '-m',