Strange diagnostic

["Nikita V. Youshchenko" <yoush@cs.msu.su>]

Hello.

Please look at the following situation:

nikita@sercond:~> ls -l /usr/local/sbin/restart-after-upgrade
-rwxr--r--    1 root     root         1044 Ноя 11  2001 
/usr/local/sbin/restart-after-upgrade*
nikita@sercond:~> which restart-after-upgrade
/usr/local/sbin/restart-after-upgrade
nikita@sercond:~> restart-after-upgrade
bash: /usr/local/sbin/restart-after-upgrade: /bin/bash: bad interpreter: 
Permission denied

Here 'restart-after-upgrade' is a shell script that happens to be executable 
by root only (I know user can easily source it, I am writing not about 
security but about diagnostic).

So why "which" finds it? And why error message when a user attempts to run 
it is so strange? Is that normal, or it should be filed as bug reports?