Cannot select element using both id and class

[Stephen James]

When trying to use Tag.select with both an id and class simultaneously, matches get missed.

Example:
```
from bs4 import BeautifulSoup

html = '<div id="sid" class="scls">Hello World!</div>'

soup = BeautifulSoup(html) # the issue is present regardless of the parser used

print(soup.select("#sid")) # works fine
print(soup.select(".scls")) # works fine
print(soup.select("#sid.scls")) # unexpectedly gives an empty list
print(soup.select(".scls#sid")) # also gives an empty list
```

The issue, as far as I see: if there is a "#", [the code](https://bazaar.launchpad.net/~leonardr/beautifulsoup/bs4/view/head:/bs4/element.py#L1400) assumes that there will only be a tag name and an id without the possibility of one or more classes as well. A possible fix would be to add an `elif '.' in token and '#' in token:` clause before to handle that case.

[Leonard Richardson (leonardr)]

Thanks for reporting this bug and for going deeper to suggest a solution. The CSS selector system is contributed code and for my own sanity I only add to it when a patch and test are contributed. I'm going to leave this issue open in a 'confirmed' state and if someone provides a patch or pull request I'll merge it.

[Leonard Richardson (leonardr)]

In the forthcoming 4.7.0 release, all CSS selector logic is delegated to the Soup Sieve project (https://facelessuser.github.io/soupsieve/). This should dramatically improve the overall support for CSS selectors in Beautiful Soup, and provide a responsive channel for improvements.

I'm closing this issue as of the 4.7.0 release. If it's still a problem in 4.7.0, file a bug against Soup Sieve. However, Isaac currently believes it's not a bug at all, so he'd need some more information.

[Leonard Richardson (leonardr)]

Scratch that bit about 'Isaac currently believes it's not a bug at all' -- that's a copy and paste error.

[Leonard Richardson (leonardr)]

In 4.7.0 release.

[Stephen James (stephenorjames)]

Thanks for following up on this, I can confirm that it now seems to work properly.