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I'm probably doing something wrong, but I've tried everything I can think of
without any success.
In Python 2.7, the pydoc command successfully displays help for the sqlite3
package, though it muffs the output of Gerhard Häring's name, spitting out
the original Latin-1 spelling. In Python 3.x, I get a UnicodeEncodeError for
my trouble, and it hoses my tty settings to boot, requiring a LF reset LF
sequence to put right unless I set PAGER to "cat".
Here's a sample run:
% PAGER=cat pydoc3.5 sqlite3
Traceback (most recent call last):
 File "/Users/skip/local/bin/pydoc3.5", line 5, in <module>
 pydoc.cli()
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 2591, in cli
 help.help(arg)
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 1874, in help
 elif request: doc(request, 'Help on %s:', output=self._output)
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 1612, in doc
 pager(render_doc(thing, title, forceload))
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 1412, in pager
 pager(text)
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 1428, in <lambda>
 return lambda text: pipepager(text, os.environ['PAGER'])
 File "/Users/skip/local/lib/python3.5/pydoc.py", line 1455, in pipepager
 pipe.write(text)
UnicodeEncodeError: 'ascii' codec can't encode character '\xe4' in position 600: ordinal not in range(128)
I understand the error, but I see no way to convince it to use any codec
other than "ascii". Stuff I tried:
* setting PYTHONIOENCODING to "UTF-8" (suggested by Peter Otten on c.l.py)
* setting LANG to "en_US.utf8"
This is on a Mac running Yosemite with pydoc invoked in Apple's Terminal
app. Display is fine in my browser when I run pydoc as a web server.
The source it is attempting to display has a coding cookie, so it should
know that the code is encoded using Latin-1. The problem seems to all be
about generating output.

What are sys.getfilesystemencoding(), locale.getpreferredencoding(False), os.popen('cat', 'w').encoding?

Without setting any environment variables:
>>> import sys
>>> sys.getfilesystemencoding()
'utf-8'
>>> import locale
>>> locale.getpreferredencoding(False)
'US-ASCII'
>>> import os
>>> os.popen('cat', 'w').encoding
'US-ASCII'
If I set PYTHONIOENCODING=UTF-8:
>>> import sys, locale, os
>>> sys.getfilesystemencoding()
'utf-8'
>>> locale.getpreferredencoding(False)
'US-ASCII'
>>> os.popen('cat', 'w').encoding
'US-ASCII'
If I set LANG=en_US.utf8:
>>> import sys, locale, os
>>> sys.getfilesystemencoding()
'utf-8'
>>> locale.getpreferredencoding(False)
'US-ASCII'
>>> os.popen('cat', 'w').encoding
'US-ASCII'
It appears neither of these environment variables does much in my environment.
I should point out that I just updated to Mac OS X 10.10.2 a couple
days ago. I have no idea if this problem existed before that upgrade.
Realizing that perhaps something had changed in the underlying
operating system support, I rebuilt Python 2.6 through 3.5 from
scratch. Same result.

Peter Otten posted a solution on c.l.py. The issue is that I didn't
mix my case properly when setting LANG:
hgpython% LANG=en_US.UTF-8 python3.5 -c 'import locale;
print(locale.getpreferredencoding(False))'
UTF-8
hgpython% LANG=en_US.utf8 python3.5 -c 'import locale;
print(locale.getpreferredencoding(False))'
US-ASCII

On Sun, Feb 1, 2015 at 2:19 PM, Skip Montanaro <report@bugs.python.org> wrote:
> The issue is that I didn't
> mix my case properly when setting LANG:
Actually, it's that the hyphen is required in "utf-8" or "UTF-8".

Final note here. Peter also did a bit of digging. Here's his note about
what he found on c.l.py:
The pager is invoked by os.popen(), and after some digging I find that it
uses a io.TestIOWrapper() to write the help text. This in turn uses
locale.getpreferredencoding(False), i. e. you were right to set LANG and
PYTHONIOENCODING is not relevant.
I was also able to provoke this problem on an openSuSE 12.2 system with
3.2.3 installed. In that environment (confirmed by Chris Angelico on his
Linux system), the case of "utf" didn't matter, nor did it matter if
"utf-8" was hyphenated or not. Obviously the Mac continues to be a rather
touchy system w.r.t. locale.
I don't know if Python should try to be accommodating here, but my
inclination is "no". OTOH, maybe io.TestIOWrapper should look at
PYTHONIOENCODING, or the pager should be invoked through something other
than os.popen (assuming there is a suitable replacement which does pay
attention to PYTHONIOENCODING).

Maybe because a pager sends its bytes more-or-less straight throught from input to output, the PYTHONIOENCODING (sys.stdout.encoding?) should be used for the TextIOWrapper to the pager’s input in this case. I’m not so sure this should be assumed in general though.

There are few levels of this issue:
1) pydoc doesn't escape characters according to output encoding. It escapes characters uneencodable with sys.getfilesystemencoding(), but this encoding can differ from the encoding of sys.stdout or default encoding.
2) Default encoding for io.TestIOWrapper() and open() can be different from sys.getfilesystemencoding(). And it unexpectedly can be ASCII.
3) Mac OS doesn't support locales with the utf8 encoding (without hyphen).
Here is a patch which solves first level -- makes pydoc using appropriate encoding with the backslashreplace error handler.

Added a test.

Patch looks sensible to me. This is another example of where Issue 15216 would be useful (a standard way to modify the encoding settings of a stream).

In the case of this issue pydoc needs change not the encoding of stdout, but errors handler of stdout. There is similar issue with pprint (issue19100).

New changeset e7b6b1f57268 by Serhiy Storchaka in branch '3.4':
Issue #23374: Fixed pydoc failure with non-ASCII files when stdout encoding
https://hg.python.org/cpython/rev/e7b6b1f57268
New changeset affe167a45f3 by Serhiy Storchaka in branch 'default':
Issue #23374: Fixed pydoc failure with non-ASCII files when stdout encoding
https://hg.python.org/cpython/rev/affe167a45f3