dpkg-buildpackage: don't set DEB_VENDOR anymore

Packages should use the new dpkg-vendor interface and not rely
on this environment variable.

debian/changelog

@@ -70,6 +70,8 @@ dpkg (1.15.1) UNRELEASED; urgency=low
     /etc/dpkg/origins. It can be used in debian/rules to enable different
     behaviour depending on the current vendor at the time of the build.
     Closes: #498380
+    Modify dpkg-buildpackage to not set the DEB_VENDOR environment variable,
+    packages should use the dpkg-vendor program instead.
   * Ensure that the automatic patch created in format "3.0 (quilt)" is always
     well registered with quilt even when it's updated by a new call to
     dpkg-source. Thanks to Goswin von Brederlow for the initial patch.

man/dpkg-buildpackage.1

@@ -222,12 +222,6 @@ Show the usage message and exit.
 Show the version and exit.
 .
 .SH ENVIRONMENT VARIABLES
-.SS Vendor identification
-The variable \fBDEB_VENDOR\fR will be set to the name of the current vendor
-if \fI/etc/dpkg/origins/default\fR exists and can be used to look up the vendor
-name. If the variable already exists, and contains the name of an existing
-vendor in \fI/etc/dpkg/origins\fR, it will be kept; otherwise the variable is
-unset.
 .SS Variables set by dpkg-architecture
 \fBdpkg\-architecture\fP is called with the \fB\-a\fP and \fB\-t\fP
 parameters forwarded. Any variable that is output by its \fB\-s\fP

scripts/dpkg-buildpackage.pl

@@ -14,7 +14,6 @@ use Dpkg::Compression;
 use Dpkg::Version qw(check_version);
 use Dpkg::Changelog qw(parse_changelog);
 use Dpkg::Arch qw(get_build_arch debarch_to_gnutriplet);
-use Dpkg::Vendor qw(get_current_vendor);
 
 textdomain("dpkg-dev");
 
@@ -321,13 +320,6 @@ if ($targetgnusystem and
                                "/usr/share/pkgconfig/";
 }
 
-my $vendor = get_current_vendor();
-if (defined $vendor) {
-    $ENV{'DEB_VENDOR'} = $vendor;
-} else {
-    delete $ENV{'DEB_VENDOR'};
-}
-
 my $arch;
 unless ($sourceonly) {
     $arch = mustsetvar($ENV{'DEB_HOST_ARCH'}, _g('host architecture'));