EHN: Improved thread safety for read_html() GH16928

Author: 3553x

Diff for: pandas/io/html.py

@@ -37,8 +37,6 @@ def _importers():
     if _IMPORTS:
         return
 
-    _IMPORTS = True
-
     global _HAS_BS4, _HAS_LXML, _HAS_HTML5LIB
 
     try:
@@ -59,6 +57,8 @@ def _importers():
     except ImportError:
         pass
 
+    _IMPORTS = True
+
 
 #############
 # READ HTML #