Recently emerging package =dev-lang/go-1.13.4 under Gentoo failed on one of our virtual servers with:

--- /usr/lib/go/test/fixedbugs/issue27836.dir/
Traceback (most recent call last):
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/_MergeProcess.py", line 234, in _spawn
    prev_mtimes=self.prev_mtimes, counter=counter)
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/vartree.py", line 1788, in wrapper
    return f(self, *args, **kwargs)
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/vartree.py", line 5385, in merge
    counter=counter)
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/vartree.py", line 4548, in treewalk
    rval = self._merge_contents(srcroot, destroot, cfgfiledict)
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/vartree.py", line 4828, in _merge_contents
    self.settings["EPREFIX"].lstrip(os.sep), cfgfiledict, mymtime):
  File "/usr/lib64/python3.6/site-packages/portage/dbapi/vartree.py", line 5225, in mergeme
    encoding=_encodings['merge'])
  File "/usr/lib64/python3.6/site-packages/portage/util/movefile.py", line 256, in movefile
    selinux.rename(src, dest)
  File "/usr/lib64/python3.6/site-packages/portage/__init__.py", line 246, in __call__
    rval = self._func(*wrapped_args, **wrapped_kwargs)
  File "/usr/lib64/python3.6/site-packages/portage/_selinux.py", line 71, in rename
    os.rename(src, dest)
UnicodeEncodeError: 'ascii' codec can't encode character '\xc4' in position 83: ordinal not in range(128)

>>> Failed to install dev-lang/go-1.13.4, Log file:

>>>  '/var/tmp/portage/dev-lang/go-1.13.4/temp/build.log'

The above log shows that the emerge fails in the installation phase when moving the files to the proper path in the system. The problem there is a non-ASCII character in the file name or path, but the environment is set to use ASCII as language.

The solution is to check if the environment LANG is set and what it contains. In this case, we should set the LANG environment to utf8.

export LANG=en_US.UTF-8

Most of the cases this kind of error could occur with virtual servers, docker (or the other kind of containers like lxc, podman and so on) containers and chroot jails or screens with changed user with su or sudo! In our case, the LANG just got missed because of a switch user procedure in a container and the emerge failed with the above error. When the LANG is missing probably the default value is “C”. In fact, check not only LANG but also the “LC_ALL” environment variable (it may have different value, which is wrong!), which also should be “en_US.UTF-8”:

export LC_ALL=en_US.UTF-8

Or try removing it at all with

unset LC_ALL

Note about the locale support

We use here “en_US.UTF-8”, because we have installed our system with this locale support, but you may use other locale support in your environment. You can chech the locale support in your system in the file – /etc/locale.gen or with the command:

[root@logs ~]# locale -a
C
C.utf8
en_AG
en_AU
en_AU.utf8
en_BW
en_BW.utf8
en_CA
en_CA.utf8
en_DK
en_DK.utf8
en_GB
en_GB.iso885915
en_GB.utf8
en_HK
en_HK.utf8
en_IE
en_IE@euro
en_IE.utf8
en_IL
en_IN
en_NG
en_NZ
en_NZ.utf8
en_PH
en_PH.utf8
en_SC.utf8
en_SG
en_SG.utf8
en_US
en_US.iso885915
en_US.utf8
en_ZA
en_ZA.utf8
en_ZM
en_ZW
en_ZW.utf8
POSIX

The above command is executed under CentOS Linux release 8.0.1905 (Core).