Fix error handling with new slapos.recipe.build when download fails

slapos/recipe/cmmi/__init__.py

@@ -313,6 +313,7 @@ class Recipe(object):
                 opt['shared'] = 'false'
                 downloadunpacked.Recipe(self.buildout, self.name, opt).install()
             except:
+                if os.path.exists(compile_dir):
                     shutil.rmtree(compile_dir)
                 raise
         else: