Roll Depot Tools from 970bf5ad2cd0 to a1e15498cd2d (3 revisions)

https://chromium.googlesource.com/chromium/tools/depot_tools.git/+log/970bf5ad2cd0..a1e15498cd2d

2020-09-11 norberg@google.com Xcode 12b3 (and later) emits arm64e binaries; try that architecture.
2020-09-11 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2020-09-11 gbeaty@chromium.org Handle failures in the bot_update script.

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/depot-tools-chromium-autoroll
Please CC ehmaldonado@google.com,sokcevic@google.com,ajp@google.com,apolito@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Bug: chromium:1103236
Tbr: ehmaldonado@google.com,sokcevic@google.com,ajp@google.com,apolito@google.com
Change-Id: Idf4caf8972aee38b8a1fe619feefdc410058d8d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2406897Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#806420}

DEPS

@@ -896,7 +896,7 @@ deps = {
   },
 
   'src/third_party/depot_tools':
-    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '970bf5ad2cd0d54f9c8fb5600cf5a799e2b75e4b',
+    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + 'a1e15498cd2dd4b2cc8826e65dbee2c2b0b63aa9',
 
   'src/third_party/devtools-frontend/src':
     Var('chromium_git') + '/devtools/devtools-frontend' + '@' + Var('devtools_frontend_revision'),