absNormPath "/" "/.." does not remove all dotdots

[nomeata]

Joey reported this issue at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=599675 against version 1.1.0.3:

Prelude System.Path> absNormPath "/" "/.."
Just "/.."
Prelude System.Path> absNormPath "/" "/../../"
Just "/"
Prelude System.Path> absNormPath "/" "/../.."
Just "/"
Prelude System.Path> absNormPath "/" "/../../../"
Nothing

I'd expect to get Nothing or "/" for all of these. The documentation
says that it removes all dotdot entries.