Backing out most recent attempt at bug 194045 (not 192688 as earlier comment said), it busted seamonkey/creature.

config/make-jars.pl

@@ -80,6 +80,9 @@ my $jarDir = $chromeDir;
 if (defined($::opt_j)) {
     $jarDir = $::opt_j;
 }
+if ($jarDir !~ /^\//) {
+    $jarDir = getcwd() . '/' . $jarDir;
+}
 
 my $verbose = 0;
 if (defined($::opt_v)) {
@@ -215,7 +218,7 @@ sub JarIt
 {
     my ($destPath, $jarPath, $jarfile, $args, $overrides) = @_;
     my $oldDir = cwd();
-    my $jarchive = _moz_abs2rel("$jarPath/$jarfile.jar", "$destPath/$jarfile", 1);
+    my $jarchive = $jarPath . '/' . $jarfile . '.jar';
     chdir("$destPath/$jarfile");
 
     if ("$fileformat" eq "flat" || "$fileformat" eq "symlink") {
@@ -231,6 +234,7 @@ sub JarIt
     mozLock($lockfile) if (!$nofilelocks);
 
     if (!($args eq "")) {
+        my $cwd = getcwd;
         my $err = 0; 
 
         #print "$zipprog $zipmoveopt -uX $jarchive $args\n";
@@ -286,26 +290,24 @@ sub JarIt
 
 sub _moz_rel2abs
 {
-    my ($path, $isdir) = @_;
-    $path = File::Spec->catfile(getcwd, $path)
-        unless File::Spec->file_name_is_absolute($path);
-    my (@dirs) = reverse split(m:/:, File::Spec->canonpath($path));
-    shift @dirs unless $isdir;
+    my ($path, $keep_file) = @_;
+    $path = File::Spec->rel2abs($path, $objdir);
+    my ($volume, $dirs, $file) = File::Spec->splitpath($path);
+    my (@dirs) = reverse File::Spec->splitdir($dirs);
     my ($up) = File::Spec->updir();
     foreach (reverse 0 .. $#dirs) {
       splice(@dirs, $_, 2) if ($dirs[$_] eq $up);
     }
-    return reverse @dirs;
+    $dirs = File::Spec->catdir(reverse @dirs);
+    return File::Spec->catpath($volume, $dirs, $keep_file && $file);
 }
 
 sub _moz_abs2rel
 {
-    my ($target, $basedir, $isdir) = @_;
-    my (@target) = _moz_rel2abs($target, 1);
-    my (@basedir) = _moz_rel2abs($basedir, $isdir);
-    shift @target, shift @basedir
-        while @target && @basedir && $target[0] eq $basedir[0];
-    return File::Spec->catfile((File::Spec->updir()) x @basedir, @target);
+    my ($target, $linkname) = @_;
+    $target = _moz_rel2abs($target, 1);
+    $linkname = _moz_rel2abs($linkname);
+    return File::Spec->abs2rel($target, $linkname);
 }
 
 sub UniqIt