Reland "Reland "Expand variables in gclient flattened output.""

This is a reland of ff6222444366463e2e86fd8b9c26580f689f78d6
should_process was set to None in the previous attempt, so CIPD dependencies were not processed.
This CL fixed that.

Original change's description:
> Reland "Expand variables in gclient flattened output."
>
> This is a reland of a32f98e652d5e151f70d571cf046c3d83ae2f486
>
> Original change's description:
> > Expand variables in gclient flattened output.
> >
> > Bug: 848990
> > Change-Id: I0ad7e4f965973edbc5a335bd30f9cbd7b04abff2
> > Reviewed-on: https://chromium-review.googlesource.com/1085996
> > Reviewed-by: Michael Moss <mmoss@chromium.org>
> > Reviewed-by: Aaron Gable <agable@chromium.org>
> > Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
>
> Tbr: agable@chromium.org
> Bug: 848990
> Change-Id: I7843544b79b2ab7e2046c187d13ea3eb65fc1b7d
> Reviewed-on: https://chromium-review.googlesource.com/1085975
> Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

Bug: 848990
Change-Id: Ic804be1b84bf8402a741a4189b60372075dfb6f3
Reviewed-on: https://chromium-review.googlesource.com/1087368
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
diff --git a/roll_dep.py b/roll_dep.py
index 982d533..82331a8 100755
--- a/roll_dep.py
+++ b/roll_dep.py
@@ -225,7 +225,7 @@
     # First gather all the information without modifying anything, except for a
     # git fetch.
     deps_path, deps_content = get_deps(current_dir)
-    gclient_dict = gclient_eval.Exec(deps_content, True, deps_path)
+    gclient_dict = gclient_eval.Exec(deps_content, deps_path)
     is_relative = gclient_dict.get('use_relative_paths', False)
     root_dir = current_dir if is_relative else gclient_root
     rolls = {}