Fixed #27195 -- Stopped dropping default when adding a nullable column.

Thanks Rob Golding from Zapier for the report.

1 files changed, 1 insertions, 1 deletions

diff --git a/django/db/backends/base/schema.py b/django/db/backends/base/schema.py
index aae64e3be7..ce929fd4e4 100644
--- a/django/db/backends/base/schema.py
+++ b/django/db/backends/base/schema.py
@@ -420,7 +420,7 @@ class BaseDatabaseSchemaEditor(object):
         self.execute(sql, params)
         # Drop the default if we need to
         # (Django usually does not use in-database defaults)
-        if not self.skip_default(field) and field.default is not None:
+        if not self.skip_default(field) and self.effective_default(field) is not None:
             sql = self.sql_alter_column % {
                 "table": self.quote_name(model._meta.db_table),
                 "changes": self.sql_alter_column_no_default % {