remove fetch-depth from wrong step, add todo to other fetch-depth step

Author: lobsterkatie

.github/workflows/build.yml

@@ -213,6 +213,10 @@ jobs:
     steps:
       - name: Check out current commit (${{ github.sha }})
         uses: actions/checkout@v2
+        # TODO: removing `fetch-depth` below seems to have no effect, and the commit which added it had no description,
+        # so it's not clear why it's necessary. That said, right now ember tests are xfail, so it's a little hard to
+        # tell if it's safe to remove. Once ember tests are fixed, let's try again with it turned off, and if all goes
+        # well, we can pull it out.
         with:
           fetch-depth: 0
       - name: Set up Node
@@ -223,7 +227,6 @@ jobs:
           # that. If it passes, newer versions of Node should also be fine. This saves us from having to run the Ember
           # tests in our Node matrix above.
           node-version: '10'
-          fetch-depth: 0
       - name: Check dependency cache
         uses: actions/cache@v2
         with: