py3: use stringutil.pprint() to print NoneType Before this patch, when running test-debugcommands.t, we get a TypeError because NoneType can't be converted into bytes. This patch uses stringutil.pprint() to print the ui._colormode. We are now close to getting test-debugcommands.t passing on Python 3. Differential Revision: https://phab.mercurial-scm.org/D3831