Take the first item of single value only with 'in' operator

Closes #13403
(grafted from d826376d08a50b415a2c4b878a2c7652f1f2083b)

--HG--
branch : 7.0

sao/src/common.js

@@ -2793,7 +2793,9 @@
                         (single_value && operator == 'in' && value.length == 1)) &&
                     (!count ||
                         ((count === 1) && model.length && name.endsWith('.id')))) {
-                    value = operator == '=' ? value : value[0];
+                    if ((operator == 'in') && single_value) {
+                        value = value[0];
+                    }
                     if (model.length && name.endsWith('.id')) {
                         model = model[0];
                         value = [model, value];

tryton/tryton/common/domain_inversion.py

@@ -433,7 +433,8 @@ def unique_value(domain, single_value=True):
                         and operator == 'in' and len(value) == 1))
                 and (not count
                     or (count == 1 and model and name.endswith('.id')))):
-            value = value if operator == '=' and single_value else value[0]
+            if operator == 'in' and single_value:
+                value = value[0]
             if model and name.endswith('.id'):
                 model = model[0]
                 value = [model, value]