> virtualenv --always-copy --verbose /tmp/tgc
> Using base prefix '/usr'
> Creating /tmp/tgc/lib/python3.6
> Cannot find file lib (bad symlink)
> Symlinking Python bootstrap modules
>   Copying to /tmp/tgc/lib/python3.6/lib-dynload
>   Creating parent directories for /tmp/tgc/lib64/python3.6
>   Copying to /tmp/tgc/lib64/python3.6/os.py
>   Ignoring built-in bootstrap module: posix
>   Copying to /tmp/tgc/lib64/python3.6/posixpath.py
>   Cannot import bootstrap module: nt
>   Copying to /tmp/tgc/lib64/python3.6/ntpath.py
>   Copying to /tmp/tgc/lib64/python3.6/genericpath.py
>   Copying to /tmp/tgc/lib64/python3.6/fnmatch.py
>   Copying to /tmp/tgc/lib64/python3.6/locale.py
>   Copying to /tmp/tgc/lib64/python3.6/encodings
>   Copying to /tmp/tgc/lib64/python3.6/codecs.py
>   Copying to /tmp/tgc/lib64/python3.6/stat.py
>   Cannot import bootstrap module: UserDict
>   Creating parent directories for /tmp/tgc/lib64/python3.6/lib-dynload
>   Copying to /tmp/tgc/lib64/python3.6/lib-dynload/readline.cpython-36m-x86_64-linux-gnu.so
>   Cannot import bootstrap module: copy_reg
>   Copying to /tmp/tgc/lib64/python3.6/types.py
>   Copying to /tmp/tgc/lib64/python3.6/re.py
>   Cannot import bootstrap module: sre
>   Copying to /tmp/tgc/lib64/python3.6/sre_parse.py
>   Copying to /tmp/tgc/lib64/python3.6/sre_constants.py
>   Copying to /tmp/tgc/lib64/python3.6/sre_compile.py
>   Copying to /tmp/tgc/lib64/python3.6/lib-dynload/zlib.cpython-36m-x86_64-linux-gnu.so
>   Cannot import bootstrap module: _abcoll
>   Copying to /tmp/tgc/lib64/python3.6/warnings.py
>   Copying to /tmp/tgc/lib64/python3.6/linecache.py
>   Copying to /tmp/tgc/lib64/python3.6/abc.py
>   Copying to /tmp/tgc/lib64/python3.6/io.py
>   Copying to /tmp/tgc/lib64/python3.6/_weakrefset.py
>   Copying to /tmp/tgc/lib64/python3.6/copyreg.py
>   Copying to /tmp/tgc/lib64/python3.6/tempfile.py
>   Copying to /tmp/tgc/lib64/python3.6/random.py
>   Copying to /tmp/tgc/lib64/python3.6/__future__.py
>   Copying to /tmp/tgc/lib64/python3.6/collections
>   Copying to /tmp/tgc/lib64/python3.6/keyword.py
>   Copying to /tmp/tgc/lib64/python3.6/tarfile.py
>   Copying to /tmp/tgc/lib64/python3.6/shutil.py
>   Copying to /tmp/tgc/lib64/python3.6/struct.py
>   Copying to /tmp/tgc/lib64/python3.6/copy.py
>   Copying to /tmp/tgc/lib64/python3.6/tokenize.py
>   Copying to /tmp/tgc/lib64/python3.6/token.py
>   Copying to /tmp/tgc/lib64/python3.6/functools.py
>   Copying to /tmp/tgc/lib64/python3.6/heapq.py
>   Copying to /tmp/tgc/lib64/python3.6/bisect.py
>   Copying to /tmp/tgc/lib64/python3.6/weakref.py
>   Copying to /tmp/tgc/lib64/python3.6/reprlib.py
>   Copying to /tmp/tgc/lib64/python3.6/base64.py
>   Copying to /tmp/tgc/lib64/python3.6/_dummy_thread.py
>   Copying to /tmp/tgc/lib64/python3.6/hashlib.py
>   Copying to /tmp/tgc/lib64/python3.6/hmac.py
>   Copying to /tmp/tgc/lib64/python3.6/imp.py
>   Copying to /tmp/tgc/lib64/python3.6/importlib
>   Copying to /tmp/tgc/lib64/python3.6/rlcompleter.py
>   Copying to /tmp/tgc/lib64/python3.6/operator.py
>   Copying to /tmp/tgc/lib64/python3.6/_collections_abc.py
>   Copying to /tmp/tgc/lib64/python3.6/_bootlocale.py
>   Copying to /tmp/tgc/lib64/python3.6/enum.py
> Creating /tmp/tgc/lib/python3.6/site-packages
> Writing /tmp/tgc/lib64/python3.6/site.py
> Writing /tmp/tgc/lib64/python3.6/orig-prefix.txt
> Writing /tmp/tgc/lib64/python3.6/no-global-site-packages.txt
> Creating /tmp/tgc/bin
> New python executable in /tmp/tgc/bin/python3
> Changed mode of /tmp/tgc/bin/python3 to 0o755
> Also creating executable in /tmp/tgc/bin/python
> Changed mode of /tmp/tgc/bin/python to 0o755
> Copying to /tmp/tgc/bin/python
> Copying to /tmp/tgc/bin/python3.6
> Testing executable with /tmp/tgc/bin/python3 -c "import sys;out=sys.stdout;getattr(out, "buffer", out).write(sys.prefix.encode("utf-8"))"
> Got sys.prefix result: '/tmp/tgc'
> Creating /tmp/tgc/lib64/python3.6/distutils
> Writing /tmp/tgc/lib64/python3.6/distutils/__init__.py
> Writing /tmp/tgc/lib64/python3.6/distutils/distutils.cfg
> Installing setuptools, pip, wheel...
>   Traceback (most recent call last):
>     File "<stdin>", line 4, in <module>
>     File "/tmp/tgc/lib64/python3.6/tempfile.py", line 45, in <module>
>       from random import Random as _Random
>     File "/tmp/tgc/lib64/python3.6/random.py", line 42, in <module>
>       from math import log as _log, exp as _exp, pi as _pi, e as _e, ceil as _ceil
>   ModuleNotFoundError: No module named 'math'
>   Complete output from command /tmp/tgc/bin/python3 - setuptools pip wheel:
>   Traceback (most recent call last):
>   File "<stdin>", line 4, in <module>
>   File "/tmp/tgc/lib64/python3.6/tempfile.py", line 45, in <module>
>     from random import Random as _Random
>   File "/tmp/tgc/lib64/python3.6/random.py", line 42, in <module>
>     from math import log as _log, exp as _exp, pi as _pi, e as _e, ceil as _ceil
> ModuleNotFoundError: No module named 'math'
> ----------------------------------------
> ...Installing setuptools, pip, wheel...done.
> Traceback (most recent call last):
>   File "/usr/bin/virtualenv", line 11, in <module>
>     sys.exit(main())
>   File "/usr/lib/python3.6/site-packages/virtualenv.py", line 712, in main
>     symlink=options.symlink)
>   File "/usr/lib/python3.6/site-packages/virtualenv.py", line 947, in create_environment
>     download=download,
>   File "/usr/lib/python3.6/site-packages/virtualenv.py", line 904, in install_wheel
>     call_subprocess(cmd, show_stdout=False, extra_env=env, stdin=SCRIPT)
>   File "/usr/lib/python3.6/site-packages/virtualenv.py", line 796, in call_subprocess
>     % (cmd_desc, proc.returncode))
> OSError: Command /tmp/tgc/bin/python3 - setuptools pip wheel failed with error code 1

See also https://github.com/pypa/virtualenv/issues/1192
Solved upstream with https://github.com/pypa/virtualenv/pull/1189