dpkg-buildpackage: Make -j override any parallel option in DEB_BUILD_OPTIONS

The commit a24fa4c525934922a6035470556051d50ad4da02 changed the
semantics in the opposite direction. Which does not make any sense
at all, and goes against any current practice.

debian/changelog

@@ -8,6 +8,8 @@ dpkg (1.18.1) UNRELEASED; urgency=low
   * Fix setting the SE Linux context when a file has a statoverride.
     Closes: #786435
   * Set the SE Linux file context even when the file mode has no file type.
+  * Make dpkg-buildpackage -j override any parallel option specified in
+    DEB_BUILD_OPTIONS. Regression introduced in dpkg 1.14.15.
   * Perl modules:
     - Add missing strict and warnings pragmas for submodules.
     - Use non-destructive substitutions inside map.

man/dpkg-buildpackage.1

@@ -193,9 +193,8 @@ failures.
 Also adds \fBparallel=\fP\fIjobs\fP or
 \fBparallel\fP to the \fBDEB_BUILD_OPTIONS\fP environment variable which
 allows debian/rules files to use this information for their own purposes.
-The \fB\%parallel=\fP\fIjobs\fP or \fBparallel\fP option in
-\fBDEB_BUILD_OPTIONS\fP environment variable will override the \fB\-j\fP
-value if this option is given.
+The \fB\-j\fP value will override the \fBparallel=\fP\fIjobs\fP or
+\fBparallel\fP option in the \fBDEB_BUILD_OPTIONS\fP environment variable.
 Note that the \fBauto\fP value will get replaced by the actual number of
 currently active processors, and as such will not get propagated to any
 child process. If the number of online processors cannot be inferred then

scripts/dpkg-buildpackage.pl

@@ -395,7 +395,6 @@ if (defined $parallel) {
         $parallel = qx(getconf _NPROC_ONLN 2>/dev/null) if $?;
         chomp $parallel;
     }
-    $parallel = $build_opts->get('parallel') if $build_opts->has('parallel');
     $ENV{MAKEFLAGS} //= '';
     $ENV{MAKEFLAGS} .= " -j$parallel";
     $build_opts->set('parallel', $parallel);