Fix modularization regression

Author: kwankyu

src/sage/features/sloane_database.py

@@ -40,15 +40,18 @@ def __init__(self):
 
     def _is_present(self):
         r"""
-        Return whether the database is installed.
+        Return whether the database is available.
 
         EXAMPLES::
 
             sage: from sage.features.sloane_database import SloaneOEIS
             sage: bool(SloaneOEIS().is_present())  # optional - !sloane_database
             False
         """
-        from sage.databases.sloane import SloaneEncyclopedia
+        try:
+            from sage.databases.sloane import SloaneEncyclopedia
+        except ImportError:
+            return False
         return SloaneEncyclopedia.is_installed()