regex does not honour escaped characters?

[Oliver Schröder]

Hello List,

I'm trying to match a User-Name attribute against a regex in the hints 
file. I'm now stumbling over a regex which does not work as expected. It 
looks like this:

DEFAULT User-Name =~ "(.*\.de\.de$)"
         Hint := "Blacklist"

It is aimed to match User-Names like "x at whatever.de.de". To my 
astonishment, it also matches usernames like "x at ende.de" (note the 
missing dot).

I'm unsing a self-compiled freeradius from git-sources:

FreeRADIUS Version 2.1.12, for host i686-pc-linux-gnu

Looking at the config.log, I assume that the local posix regex functions 
are used:

   $ grep regex config.log
configure:23003: checking regex.h usability
configure:23044: checking regex.h presence
configure:23107: checking for regex.h
ac_cv_header_regex_h=yes

 From my observations, it seems that backslashes are removed from the 
regex string before the regex gets compiled, but I might be wrong.

Am I missing something or is this a (known) bug?