Fix path split.

`path` split by `,` , if fails error of included path of ` `(whitespace) or `,`.

> `:help path`

> Spaces can also be used to separate directory names (for backwards
> compatibility with version 3.0).  To have a space in a directory
> name, precede it with an extra backslash, and escape the space:
> ```vim
> :set path=.,/dir/with\\\ space
> ```

> To include a comma in a directory name precede it with an extra
> backslash:
> ```vim
> :set path=.,/dir/with\\,comma
> ```