dpkg-genchanges: Fix error message on empty dsc file

Pass the argument for the format string to the correct function call.

debian/changelog

@@ -202,6 +202,7 @@ dpkg (1.18.0) UNRELEASED; urgency=low
     - Say substvars instead of varlist in dpkg-shlibdeps error messages.
     - Fix error messages on invalid uid/git/mode command-line syntax errors
       in dpkg-statoverride, to not say they are from the statoverride file.
+    - Fix error message on empty dsc file in dpkg-genchanges.
 
   [ Raphaël Hertzog ]
   * Drop myself from Uploaders.

scripts/dpkg-genchanges.pl

@@ -277,7 +277,7 @@ if ($include & BUILD_SOURCE) {
     my $dsc = "${spackage}_${sversion}.dsc";
     my $dsc_pathname = "$uploadfilesdir/$dsc";
     my $dsc_fields = Dpkg::Control->new(type => CTRL_PKG_SRC);
-    $dsc_fields->load($dsc_pathname) or error(g_('%s is empty', $dsc_pathname));
+    $dsc_fields->load($dsc_pathname) or error(g_('%s is empty'), $dsc_pathname);
     $checksums->add_from_file($dsc_pathname, key => $dsc);
     $checksums->add_from_control($dsc_fields, use_files_for_md5 => 1);