6.5.0 fails to properly parse ruby-3.2.0 source directory

[gromnitsky]

$ ruby -v
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]

$ gem install rdoc -v 6.5.0
$ gem install rdoc -v 6.4.0

$ wget https://cache.ruby-lang.org/pub/ruby/3.2/ruby-3.2.0.tar.gz
$ tar xf ruby-3.2.0.tar.gz
$ cd ruby-3.2.0

Then, testing with v6.5.0 yields:

$ rdoc _6.5.0_ -r -o 650
$ find 650 -type f | wc -l
81

which is obviously not quite right.

But with v6.4.0 everything seems to work fine:

$ rdoc _6.4.0_ -r -o 640
$ find 640 -type f | wc -l
11227