Encoding issues while doing bundle install

It isn't done because it shouldn't have to be, it's more or less your
systems job to inform Ruby what your encoding preference is. Even
though I would love to say that UTF-8 is the encoding for the entire
world I can't and I can say that enforcing UTF-8 would be an
anti-pattern (to me) even if it's the preferred. If you are on Linux
or Unix read the following... if you are on Windows you are on your
own because I know about as much about Windows as actually I don't
really know much about Windows other than the lowlevel userland API's.

[9:12:55] jordon@me:~ % export LANG="en_US.BROKEN"
[9:13:00] jordon@me:~ % ruby -e 'p __ENCODING__'
#<Encoding:US-ASCII>

[9:13:02] jordon@me:~ % export LANG="en_US.UTF-8"
[9:13:09] jordon@me:~ % ruby -e 'p __ENCODING__'
#<Encoding:UTF-8>

[9:14:20] jordon@me:~ % export LANG="en_US.BROKEN"
[9:14:24] jordon@me:~ % export LC_CTYPE="en_US.UTF-8"
[9:14:31] jordon@me:~ % printenv |grep -P LANG\|LC_
LANG=en_US.BROKEN
LC_CTYPE=en_US.UTF-8
[9:14:50] jordon@gryffindor:~ % ruby -e 'p __ENCODING__'
#<Encoding:UTF-8>

Make sure LANG and/or LC_CTYPE are set.
LC_CTYPE="en_US.UTF-8"
LANG="en_US.UTF-8"

Some applications expect LC_CTYPE some expect LANG some will expect
either or and LC_CTYPE overrides LANG.