Bug 1312384

Description of problem:
Mock using environment variable:
  config_opts['environment']['PROMPT_COMMAND'] = 'printf "\033]0;<mock-chroot>\007<mock-chroot>"'
See bug 1126235 for history if you want to know why.

And when I use systemd-nspawn in mock. (--new-chroot option) It will execute:
DEBUG: doshell: command: ['/usr/bin/systemd-nspawn', '-q', '-M', '1b48214dd52d4132aa711e3408619c74', '-D', '/var/lib/mock/epel-7-x86_64/root', '--setenv=FOO=BAR', '--setenv=HOSTNAME=mock', '--setenv=PROMPT_COMMAND=printf "\x1b]0;<mock-chroot>\x07<mock-chroot>"', '--setenv=SHELL=/bin/bash', '--setenv=PATH=/usr/bin:/usr/sbin', '--setenv=TERM=vt100', '--setenv=LANG=cs_CZ.UTF-8', '--setenv=HOME=/builddir', '/bin/sh', '-i', '-l']
Note that this is not even master. I discovered that during work on mock bug 1311796.

Which will fails with:
  Environment variable assignment 'PROMPT_COMMAND=printf "<mock-chroot>"' is not valid.

I suppose that it is because you check if the character is UTF.

Version-Release number of selected component (if applicable):
systemd-222-14.fc23.x86_64

How reproducible:
always

Steps to Reproduce:
1. systemd-nspawn -q -M 1b48214dd52d4132aa711e3408619c74 -D /var/lib/mock/epel-7-x86_64/root '--setenv=PROMPT_COMMAND=printf "\x1b]0;<mock-chroot>\x07<mock-chroot>"'

Actual results:
variable is not valid

Expected results:
no errors because that variable is perfectly valid

Additional info:
Until this get resolved Mock will use simpler PROMPT for nspawn.