avoid broken sources lists on bad config

git-svn-id: http://emdebian.org/svn/current@7123 563faec7-e20c-0410-992a-a66f704d0ccd

multistrap

@@ -260,6 +260,8 @@ foreach my $aptsrc (@debootstrap)
 		$mirror = $sources{$aptsrc};
 		$suite = $suites{$aptsrc};
 		$component = (defined $components{$aptsrc}) ? $components{$aptsrc} : "main";
+		if (defined $mirror and defined $suite)
+		{
 			print SOURCES<<END;
 deb $mirror $suite $component
 deb-src $mirror $suite $component
@@ -267,6 +269,7 @@ END
 			close SOURCES;
 		}
 	}
+}
 my $k;
 foreach my $pkg (values %keyrings)
 {
@@ -398,6 +401,7 @@ foreach my $aptsrc (@aptsources)
 		$mirror = $sources{$aptsrc};
 		$suite = $suites{$aptsrc};
 		$component = (defined $components{$aptsrc}) ? $components{$aptsrc} : "main";
+		if (defined $mirror and defined $suite)
 			print SOURCES<<END;
 deb $mirror $suite $component
 deb-src $mirror $suite $component
@@ -405,6 +409,7 @@ END
 			close SOURCES;
 		}
 	}
+}
 # altered the sources, so get apt to update.
 (not defined $tidy) ? system ("apt-get $config_str update") : &tidy_apt;