[gnome-builder] rustup: check for clean exit before exit status

[Christian Hergert <chergert src gnome org>]

commit 9fbdd624ae0a95cbf12119e6af0d99b09bd51384
Author: Christian Hergert <chergert redhat com>
Date:   Sun Mar 19 15:06:20 2017 -0700

    rustup: check for clean exit before exit status
    
    You have to check if the process exited cleanly before trying to get the
    exit status.

 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 f131a0e..827c2ff 100644
--- a/plugins/rustup/rustup_plugin/__init__.py
+++ b/plugins/rustup/rustup_plugin/__init__.py
@@ -406,7 +406,7 @@ class RustupInstaller(Ide.Transfer):
     def _wait_cb(self, sub_process, result, task):
         try:
             sub_process.wait_check_finish(result)
-            if sub_process.get_exit_status() == 0:
+            if sub_process.get_if_exited() and sub_process.get_exit_status() == 0:
                 task.return_boolean(True)
             else:
                 if self.mode == _MODE_INSTALL_TOOLCHAIN: