[MIGR][l10n_br_account] minor compatibility fix in account_fiscal_position_rule.py
[MIGR][l10n_br_account] minor compatibility fix in account_fiscal_position_rule.py

akretion/l10n-brazil,akretion/l10n-brazil,OCA/l10n-brazil,akretion/l10n-brazil,OCA/l10n-brazil,OCA/l10n-brazil