anchor.diff:    buildInputs = [ coreutils db openssl perl pcre ]
       ++ stdenv.lib.optional enableLDAP openldap
       ++ stdenv.lib.optionals enableMySQL [ mysql zlib ]
  -    ++ stdenv.lib.optional enableAuthDovecot dovecot;
  +    ++ stdenv.lib.optional enableAuthDovecot dovecot
  +    ++ stdenv.lib.optional enablePAM pam;
   
     preBuild = ''
       ${stdenv.lib.optionalString enableMySQL "PKG_CONFIG_PATH=$PKG_CONFIG_PATH:${mysql}/share/mysql/pkgconfig/"}
  
positive.code:       ${stdenv.lib.optionalString enableAuthDovecot ''
          s:^# \(AUTH_DOVECOT\)=.*:\1=yes:
        ''}
        #/^\s*#.*/d
        #/^\s*$/d
      ' < src/EDITME > Local/Makefile
  
negative.code: , enableLDAP ? false, openldap
  , enableMySQL ? false, mysql, zlib
  , enableAuthDovecot ? false, dovecot
  , enablePAM ? false, pam
  }:
  
  stdenv.mkDerivation rec {
  