gclient flatten: use original dependencies, before deps_os kicks in

Bug: 570091
Change-Id: I2b68e8e8a0e28b28b9aab79833578cdf59392b98
Reviewed-on: https://chromium-review.googlesource.com/531185Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

testing_support/fake_repos.py

@@ -474,12 +474,21 @@ deps = {
 deps_os ={
   'mac': {
     'src/none_repo': None,
+
+    # This entry should not appear in flattened DEPS' |deps|.
+    'src/os_repo': '/repo_5',
   },
   'unix': {
     'src/none_repo': None,
+
+    # This entry should not appear in flattened DEPS' |deps|.
+    'src/os_repo': '/repo_5',
   },
   'win': {
     'src/none_repo': None,
+
+    # This entry should not appear in flattened DEPS' |deps|.
+    'src/os_repo': '/repo_5',
   },
 }
 hooks = [