dpkg-source: accept "." as the directory parameter

dpkg-source should never be called from within the unpacked source
tree, the result is usually not what one would expect. Fix this
by automatically converting the directory name and by changing the
current directory to the parent one.

This is particularly interesting for the upcoming --record-changes
option.

scripts/dpkg-source.pl

@@ -11,7 +11,7 @@
 # Copyright © 2005 Brendan O'Dea <bod@debian.org>
 # Copyright © 2006-2008 Frank Lichtenheld <djpig@debian.org>
 # Copyright © 2006-2009 Guillem Jover <guillem@debian.org>
-# Copyright © 2008-2010 Raphaël Hertzog <hertzog@debian.org>
+# Copyright © 2008-2011 Raphaël Hertzog <hertzog@debian.org>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -45,6 +45,8 @@ use Dpkg::Changelog::Parse;
 use Dpkg::Source::Package;
 use Dpkg::Vendor qw(run_vendor_hook);
 
+use Cwd;
+use File::Basename;
 use File::Spec;
 
 textdomain("dpkg-dev");
@@ -104,6 +106,11 @@ if (defined($options{'opmode'}) &&
     if (not -d $dir) {
 	error(_g("directory argument %s is not a directory"), $dir);
     }
+    if ($dir eq ".") {
+	# . is never correct, adjust automatically
+	$dir = basename(cwd());
+	chdir("..") || syserr(_g("unable to chdir to `%s'"), "..");
+    }
     # --format options are not allowed, they would take precedence
     # over real command line options, debian/source/format should be used
     # instead