Ensure environment is restored on error

Fixes sds#129

Change-Id: I1947b1b508dea94fa2f1024123d16df29b6329a3
Reviewed-on: http://gerrit.causes.com/48044
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

Author: jawshooah

lib/overcommit/hook_runner.rb

@@ -22,11 +22,13 @@ def run
       # these calls to allow some sort of "are you sure?" double-interrupt
       # functionality, but until that's deemed necessary let's keep it simple.
       InterruptHandler.isolate_from_interrupts do
-        @context.setup_environment
-        load_hooks
-        result = run_hooks
-        @context.cleanup_environment
-        result
+        begin
+          @context.setup_environment
+          load_hooks
+          run_hooks
+        ensure
+          @context.cleanup_environment
+        end
       end
     end