[gnome-builder] rustup: prefer tuple over list

[Christian Hergert <chergert src gnome org>]

commit 9ccc7cb8997571e9e4c1de976ce7239c8791b38c
Author: Christian Hergert <chergert redhat com>
Date:   Sun Mar 19 16:33:07 2017 -0700

    rustup: prefer tuple over list

 plugins/rustup/rustup_plugin/__init__.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plugins/rustup/rustup_plugin/__init__.py b/plugins/rustup/rustup_plugin/__init__.py
index 33e2125..c20ea91 100644
--- a/plugins/rustup/rustup_plugin/__init__.py
+++ b/plugins/rustup/rustup_plugin/__init__.py
@@ -122,7 +122,7 @@ class RustupApplicationAddin(GObject.Object, Ide.ApplicationAddin):
             Checks if a rustup installation is available.
         """
         self.rustup_executable = None
-        for rustup_bin in ['rustup', os.path.expanduser('~/.cargo/bin/rustup')]:
+        for rustup_bin in ('rustup', os.path.expanduser('~/.cargo/bin/rustup')):
             try:
                 launcher = Ide.SubprocessLauncher.new(Gio.SubprocessFlags.STDOUT_PIPE)
                 launcher.push_argv(rustup_bin)