fix sanity.test_relooper

tests/test_sanity.py

@@ -453,6 +453,11 @@ fi
     try_delete(CANONICAL_TEMP_DIR)
 
   def test_relooper(self):
+    assert os.environ.get('EMCC_FAST_COMPILER') is None
+
+    try:
+      os.environ['EMCC_FAST_COMPILER'] = '0'
+
       RELOOPER = Cache.get_path('relooper.js')
 
       restore()
@@ -474,6 +479,8 @@ fi
           main = src.split('function _main()')[1].split('\n}\n')[0]
           assert ('while (1) {' in main or 'while(1){' in main or 'while(1) {' in main or '} while ($' in main or '}while($' in main) == (i >= 1), 'reloop code on O2: ' + main
           assert ('switch' not in main) == (i >= 1), 'reloop code on O2: ' + main
+    finally:
+      del os.environ['EMCC_FAST_COMPILER']
 
   def test_jcache(self):
     PRE_LOAD_MSG = 'loading pre from jcache'