utils.guess_filename fails if the given parameter looks like a file object but has a non-string name attribute

e.g. a cherrypy uploaded file behave like a regular file, except that its name attribute is an int and passing it directly to requests fails because of that
Merge pull request #2379 from arthurdarcet/master

utils.guess_filename fails if the given parameter looks like a file object but has a non-string name attribute
Fix a typo in a comment

I just fixed a minor typo: "throws" is misspelled as "thows".
Merge pull request #2381 from namlede/patch-1

Fix a typo in a comment