Item6379: Correct a configure bug where a defined empty string '' is converted into 'NOT SET'

This is done here in: lib/TWiki/Configure/Checkers/BasicSanity.pm

    # If we got this far without definitions for key variables, then
    # we need to default them. otherwise we get peppered with
    # 'uninitialised variable' alerts later.
    foreach my $var qw( DataDir DefaultUrlHost PubUrlPath
                        PubDir TemplateDir ScriptUrlPath LocalesDir ) {
        # NOT SET tells the checker to try and guess the value later on
        $TWiki::cfg{$var} ||= 'NOT SET';
    }

To fix we should change the line to:

        $TWiki::cfg{$var} = 'NOT SET' unless defined $TWiki::cfg{$var};

This is a small change that will only affect those who use empty strings as part of their configuration.

My ScriptUrlPath is set to an empty string.

-- TWiki:Main/VernonLyon - 30 Dec 2009

Thank you Vernon! Could you also fix the 4.3 branch?

-- TWiki:Main.PeterThoeny - 31 Dec 2009

Setting to "waiting for release" for TWiki-5.0.0.

-- TWiki:Main.PeterThoeny - 29 May 2010