Work around AIX shell builtin printf not handling \NNN.
On AIX, ksh builtin printf does not understand \NNN. Some tests use this
to generate test data, and so fail on AIX. Rework these tests to use python
to generate the correct characters. This fixes the tests on AIX and should
be more generally portable.
%% Should show unknown
? unknown
removing b
%% Should show unknown and b removed
R b
? unknown
%% Should show a and unknown
a
unknown