Fix infinite loop on empty variable name.

test/variables/empty/empty.gyp

Index: test/variables/empty/empty.gyp
diff --git a/test/errors/error_command.gyp b/test/variables/empty/empty.gyp
similarity index 66%
copy from test/errors/error_command.gyp
copy to test/variables/empty/empty.gyp
index 1736fc9882bd3184843af6a303b934c0b9cb5bad..207be06fe710ed504a9f62a46c85de05ac8d0712 100644
--- a/test/errors/error_command.gyp
+++ b/test/variables/empty/empty.gyp
@@ -3,10 +3,11 @@
 # found in the LICENSE file.
 
 {
+  'includes': ['empty.gypi'],
   'targets': [
     {
-      'target_name': 'foo',
-      'type': '<!(["python", "-c", "import sys; sys.exit(3)"])',
+      'target_name': 'empty',
+      'type': 'none',
     },
-  ]
+  ],
 }