[FIX] util/pg: fix rename_model with m2m fields

In the case of renamed model being referenced in a many2many table (for having
or being referenced in a m2m field), related `ir_model_fields.column1` (and 2)
aren't updated. However, the m2m tables column names themselves are properly
updated. This lead to an error because the `column1` is referring to a column
whose name is already overwritten, and to a crash because the returned foreign
keys list is empty but accessed at [0].

[tbg](https://upgrade.odoo.com/odoo/tbg/2156)

closes #319

Signed-off-by: Christophe Simonis (chs) <chs@odoo.com>

Author: vval-odoo

src/util/pg.py

@@ -1465,6 +1465,28 @@ def update_m2m_tables(cr, old_table, new_table, ignored_m2ms=()):
                 del_action=SQLStr("RESTRICT") if on_delete == "r" else SQLStr("CASCADE"),
             )
             cr.execute(query)
+
+            cr.execute(
+                """
+                UPDATE ir_model_fields
+                   SET column1 = %s
+                 WHERE relation_table = %s
+                   AND column1 = %s
+                   AND state = 'manual'
+                """,
+                [new_col, m2m_table, old_col],
+            )
+            cr.execute(
+                """
+                UPDATE ir_model_fields
+                   SET column2 = %s
+                 WHERE relation_table = %s
+                   AND column2 = %s
+                   AND state = 'manual'
+                """,
+                [new_col, m2m_table, old_col],
+            )
+
             _logger.info("Renamed m2m column of table %s from %s to %s", m2m_table, old_col, new_col)