apt-cache regex question

[Πρεκατές Αλέξανδρος <aprekates@gmail.com>]

 Hi  
apt-cache --names-only  search  '^a'  except from 
packages name started with 'a' (intented)  will also  give 
packages that they have a source file whos name starts with 
'a'. is that an error?


eg:
$apt-cache --names-only  search  '^a'
...
xul-ext-adblock-plus
...
 
$ apt-cache show xul-ext-adblock-pl
ackage: xul-ext-adblock-plus
Priority: optional
Section: web
Installed-Size: 1480
Maintainer: Dmitry E. Oboukhov <unera@debian.org>
Architecture: all
Source: adblock-plus
Version: 1.2.1-1


alexander.