Some users noticed an issue where, depending on their local encoding

preferences, Python 3 might not be able to write rb-site output to the

console. This could be reproduced by running with

PYTHONIOENCODING=latin1. In such encoding modes, Unicode characters

would fail to encode to the target encoding before their bytes were sent

to the underlying stdout/stderr streams.
This happened because, by default, sys.stdout and sys.stderr are

io.TextIOWrapper instances that wrap the stream, encoding any Unicode

strings with the configured encoding. PYTHONIOENCODING, amongst other

environmental factors, could influence the default encoding.
The solution is to avoid using this wrapper, and instead write to the

output stream directly. To do this correctly, we have to wrap the stream

with our own wrapper, using a hard-coded encoding of utf-8. Since

we're already taking in stream objects, this is trivial to do.
With this change, users should no longer hit issues going through

rb-site or displaying any other output on their terminals, or when

outputting to files.
Unit tests were added that check for this condition and ensure that

content is correctly encoded.

Reproduced the original problem by setting PYTHONIOENCODING=latin1 and

attempted to an install a site. Verified that it crashed with the reported

encoding errors prior to this patch, but succeeded after.
Attempted the same test with redirecting console output.
Unit tests pass.