Fix race condition in import_options test

Author: kornelski

src/imp/security_framework.rs

@@ -195,7 +195,9 @@ impl Identity {
             }
         });
 
-        let keychain = match *TEMP_KEYCHAIN.lock().unwrap() {
+        // keep it locked during import()
+        let keychain = &mut *TEMP_KEYCHAIN.lock().unwrap();
+        match keychain {
             Some((ref keychain, _)) => keychain.clone(),
             ref mut lock @ None => {
                 let dir =