Why does leapp upgrade fails in emergency with error "UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 1: ordinal not in range(128)" ?

Issue

System upgrade failed in emergency mode with below error

[  937.868119] localhost upgrade[1705]:   yum-langpacks-0.4.2-7.el7.noarch
[  941.078514] localhost upgrade[1705]:   yProcess Process-255:
[  941.078514] localhost upgrade[1705]: Traceback (most recent call last):
[  941.124397] localhost upgrade[610]:   File "/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py", line 74, in _do_run
[  941.124397] localhost upgrade[610]:     actor_instance.run(*args, **kwargs)
[  941.124397] localhost upgrade[610]:   File "/usr/lib/python2.7/site-packages/leapp/actors/__init__.py", line 289, in run
[  941.124397] localhost upgrade[610]:     self.process(*args)
[  941.124397] localhost upgrade[610]:   File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/dnfupgradetransaction/actor.py", line 63, in process
[  941.124397] localhost upgrade[610]:     shutil.rmtree(userspace.path)
[  941.124397] localhost upgrade[610]:   File "/usr/lib64/python2.7/shutil.py", line 247, in rmtree
[  941.124397] localhost upgrade[610]:     elif onerror is None:
[  941.124397] localhost upgrade[610]:   File "/usr/lib64/python2.7/shutil.py", line 247, in rmtree
[  941.124397] localhost upgrade[610]:     elif onerror is None:
[  941.124397] localhost upgrade[610]:   File "/usr/lib64/python2.7/shutil.py", line 241, in rmtree
[  941.124397] localhost upgrade[610]:     is false and onerror is None, an exception is raised.
[  941.124397] localhost upgrade[610]:   File "/usr/lib64/python2.7/posixpath.py", line 80, in join
[  941.124397] localhost upgrade[610]:     # Trailing '/'es are stripped from head unless it is the root.
[  941.124397] localhost upgrade[610]: UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 1: ordinal not in range(128)
[  941.137924] localhost upgrade[610]: ========================================================================================================
[  941.137924] localhost upgrade[610]: Actor dnf_upgrade_transaction unexpectedly terminated with exit code: 1 - Please check the above details
[  941.137924] localhost upgrade[610]: ========================================================================================================