Used CommandError in createcachetable command.

Raising CommandError whenever a management command meets an error
condition is the standard way to handle errors in commands.

django/core/management/commands/createcachetable.py

@@ -1,7 +1,7 @@
 from optparse import make_option
 
 from django.core.cache.backends.db import BaseDatabaseCache
-from django.core.management.base import LabelCommand
+from django.core.management.base import LabelCommand, CommandError
 from django.db import connections, router, transaction, models, DEFAULT_DB_ALIAS
 from django.db.utils import DatabaseError
 
@@ -55,11 +55,10 @@ class Command(LabelCommand):
         try:
             curs.execute("\n".join(full_statement))
         except DatabaseError as e:
-            self.stderr.write(
+            transaction.rollback_unless_managed(using=db)
+            raise CommandError(
                 "Cache table '%s' could not be created.\nThe error was: %s." %
                     (tablename, e))
-            transaction.rollback_unless_managed(using=db)
-        else:
-            for statement in index_output:
-                curs.execute(statement)
-            transaction.commit_unless_managed(using=db)
+        for statement in index_output:
+            curs.execute(statement)
+        transaction.commit_unless_managed(using=db)