Errors in Ubuntu 18.04

Issue: Easy Install

Errors in Ubuntu 18
Linux localhost 4.15.0-142-generic frappe/bench#146-Ubuntu SMP Tue Apr 13 01:11:19 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

It does not appear the script finished successfully.

```
WARNING: Running pip as root will break packages and permissions. You should install packages reliably by using venv: https://pip.pypa.io/warnings/venv
pip3 already installed!
WARNING: pip is being invoked by an old script wrapper. This will fail in a future version of pip.
Please see https://github.com/pypa/pip/issues/5599 for advice on fixing the underlying issue.
To avoid this problem you can invoke Python with '-m pip' instead of running pip directly.
WARNING: The directory '/home/erpnext/.cache/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.
Collecting distro
Downloading distro-1.5.0-py2.py3-none-any.whl (18 kB)
Installing collected packages: distro
Successfully installed distro-1.5.0
WARNING: Running pip as root will break packages and permissions. You should install packages reliably by using venv: https://pip.pypa.io/warnings/venv
Checking System Compatibility...
ubuntu 18 is compatible!
Bench's CLI needs these to be defined!
Run the following commands in shell:
export LC_ALL=C.UTF-8
```

The payload names no source file or test; start at the Easy Install entry point and reproduce the failure on Ubuntu 18.04 using the shown environment. Trace the system-compatibility check and the reported CLI environment-variable message, then verify whether installation completes successfully.

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