safety fix

Cython/Compiler/ModuleNode.py

@@ -346,10 +346,12 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         globalstate.finalize_main_c_code()
 
         f = open_new_file(result.c_file)
-        rootwriter.copyto(f)
-        if options.gdb_debug:
-            self._serialize_lineno_map(env, rootwriter)
-        f.close()
+        try:
+            rootwriter.copyto(f)
+            if options.gdb_debug:
+                self._serialize_lineno_map(env, rootwriter)
+        finally:
+            f.close()
         result.c_file_generated = 1
         if Options.annotate or options.annotate:
             self.annotate(rootwriter)