Leading tab / space detection shouldn't get thrown off by a single leading space.

[nedtwigg]

It is common to have a copyright header at the top of a file like this:

/* Copyright blah
 * Blah blah blah
 */

If the whole file is space-indented, that's fine. But even in a tab-indented file, it's common to have these single spaces in the copyright header at top. That should not throw off the indent detection in

• Don't escape leading whitespace if we can safely avoid it #240