My server is having problems with this file:
Because of this PHP environment variable "open_basedir"
This file does not work correctly with this variable in effect.
This is unacceptable because SO many hosting providers have this variable in a effect.
It also provides more security in general.
I found the root of the problem was that the function "get_home_path()", it is returning "/", and while testing this return with is_writable(), it is not correct because "/" is not valid within the open_basedir value.
I don't really understand why this would be anything but ABSPATH, and I didn't see any need for it to be anything else. So in "wp-admin/options-permalink.php" I replaced the value of "$home_path" with "ABSPATH".
Then it almost worked. But then I also got an error from "wp-admin/includes/misc.php" within the function "save_mod_rewrite_rules()". I did the same thing there.
Everything is fine now, with "open_basedir" still in effect.