generate_temp_url does not do URL encoding

[Adam]

swift tempurl does not do URL escaping in the URLs it generates.

If you have an object or container containing a character that needs to be escaped in a URI (eg a question mark), you must pass it unescaped in the [path] argument to "swift tempurl" - if you escape it there, the resulting TempURL is not valid for the object.

However, if you pass an unescaped value to "swift tempurl" it does not return a valid URL, because it does not apply URL encoding to the characters in the path and the special character is returned as-is.

A possible fix is to apply URL encoding to path_for_body when constructing temp_url in generate_temp_url() - but not to the / characters.