Remove xref.priority

sql/patch_41_42_a.sql

+# patch_41_42_a
+#
+# title: remove xref.priority
+#
+# description:
+# Remove the priority column in xref
+
+ALTER TABLE xref DROP COLUMN priority;
+
+# patch identifier
+INSERT INTO meta (meta_key, meta_value) VALUES ('patch', 'patch_41_42_a.sql|remove_xref_priority');
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