a KEYWORD must contain at least one character

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@19669 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/SearchKey/KeyWordKey.py

@@ -101,7 +101,7 @@ class KeyWordKey(SearchKey):
     return t
 
   def t_KEYWORD(self, t):
-    r'(%\S*|([^!<>=\s%]\S*|!([^=\s]\S*)?)%)'
+    r'(%\S*|([^!<>=\s%]\S+|!([^=\s]\S+)?)%)'
     # KEYWORD must start and/or end with '%'.
     # It may contain arbitrary letters and numbers without white space
     value = t.value.strip()