reenable support for -s (and co) in apt-get source

The conversion to accept only relevant options for commands has
forgotten another one, so adding it again even through the usecase might
very well be equally good served by --print-uris.

Closes: 742578

apt-private/private-cmndline.cc

@@ -166,7 +166,7 @@ static bool addArgumentsAPTGet(std::vector<CommandLine::Args> &Args, char const
 
    if (CmdMatches("install", "remove", "purge", "upgrade", "dist-upgrade",
 	    "deselect-upgrade", "autoremove", "clean", "autoclean", "check",
-	    "build-dep", "full-upgrade"))
+	    "build-dep", "full-upgrade", "source"))
    {
       addArg('s', "simulate", "APT::Get::Simulate", 0);
       addArg('s', "just-print", "APT::Get::Simulate", 0);

test/integration/test-apt-get-source

@@ -82,3 +82,7 @@ testequal "$HEADER
 Need to get 0 B of source archives.
 'file://${APTARCHIVE}/foo_0.0.1.dsc' foo_0.0.1.dsc 0 MD5Sum:d41d8cd98f00b204e9800998ecf8427e
 'file://${APTARCHIVE}/foo_0.0.1.tar.gz' foo_0.0.1.tar.gz 0 MD5Sum:d41d8cd98f00b204e9800998ecf8427e" aptget source -q --print-uris -t unstable foo=0.0.1
+
+testequal "$HEADER
+Need to get 0 B of source archives.
+Fetch source foo" aptget source -q -s foo