Version/language widget causes massive URLs/redirect loops

The version/language selector widget causes problems when switching languages. As it's redundant with the Translations sidebar item, maybe removing the links would be OK?
## Reproducing
1. Go to http://docs.python-requests.org/en/master/user/install/ (i.e. _not_ the home page)
2. Click "v:master"
3. Click a language (e.g. "de")
4. End up at:

```
http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master
/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/u
ser_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/use
r_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_
builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_bu
ilds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_buil
ds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds
/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/r
equests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/req
uests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/reque
sts/rtd-builds/master/user_builds/requests/translations/de/latest/user/install/i
ndex/index/index/index/index/index/index/index/index/index/index/index/index/ind
ex/index/index/index/index/index/index/index/
```
## Conditions
- Chrome 48 / Safari 9.0.3
- OS X 10.11
## Expected/Desired
1. Go to http://docs.python-requests.org/en/master/
2. Click the "v:master" version button at the bottom right
3. Click your favorite language.

or:
1. Go to http://docs.python-requests.org/en/master/user/install/
2. Click your favorite language under "Translations" on the sidebar


Uh, so I don't reproduce that with Safari. What browser are you using?


@Lukasa both Chrome and Safari according to their "Conditions" section.


How about no browser:

```
import requests

url = 'http://docs.python-requests.org/zh_CN/latest/user/install/'
for x in range(10):
    print(x, url)
    response = requests.get(url, allow_redirects=False)
    if response.status_code in (301, 302):
        url = response.headers['Location']
```

Yields:

```
0 http://docs.python-requests.org/zh_CN/latest/user/install/
1 http://docs.python-requests.org/en/master/user_builds/requests/translations/zh_CN/latest/user/install/index/
2 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/
3 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/
4 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/
5 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/index/
6 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/index/index/
7 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/index/index/index/
8 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/index/index/index/index/
9 http://docs.python-requests.org/en/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/rtd-builds/master/user_builds/requests/translations/zh_CN/latest/user/install/index/index/index/index/index/index/index/index/index/
```


So my experience of this seems to be that it occurs only when you swap languages from one of the sub pages. If you do the swap at the top level it seems to work fine.

That _seems_ to me like it's probably an RTD issue? @ericholscher am I right about that, or am I on totally the wrong track here?


I did mention that in the initial issue ;)

On RTD's own documentation I can't seem to get it to trigger, but is that because their pages are completely flat (no subfolders it seems)...can't find any other projects using RTD + localization right now.


From an initial look, the subprojects are using sphinx's HTML builder, and the main project is using HTMLDir, so that URL's don't line up when switching languages. The redirect loop however is likely a bug :) We just deployed some new nginx configs so it's likely an issue with that.

eg. http://docs.python-requests.org/zh_CN/latest/user/install.html is a URL that works.

I was just investigating a weird Nginx bug that caused this to happen when given a directory that exists but doesn't have an `index.html` file, as is the case here. I'll look at it more, but the main issue is that the URL is 404'ing in the first place.