tests/unicode_subscr.py: Detailed test for subscripting unicode strings.

tests/unicode/unicode_subscr.py

+a = '¢пр'
+
+print(a[0], a[0:1])
+print(a[1], a[1:2])
+print(a[2], a[2:3])
+try:
+    print(a[3])
+except IndexError:
+    print("IndexError")
+print(a[3:4])
+
+print(a[-1])
+print(a[-2], a[-2:-1])
+print(a[-3], a[-3:-2])
+try:
+    print(a[-4])
+except IndexError:
+    print("IndexError")
+print(a[-4:-3])
+
+print(a[0:2])
+print(a[1:3])
+print(a[2:4])