Bug 1405068: Don't use Cwd::abs_path in unwrap_full_update.pl. r=bhearsum

It is broken on the version of perl on the legacy buildbots, which is the only
place that this branch of the code runs.

MozReview-Commit-ID: 1Urw6mNOEHf

--HG--
extra : rebase_source : d599484b0f2062b7e3178e761c80b620624852a3

tools/update-packaging/unwrap_full_update.pl

@@ -12,7 +12,6 @@
 # By default just assume that these tools exist on our path
 
 use Getopt::Std;
-use Cwd 'abs_path';
 
 my ($MAR, $XZ, $BZIP2, $MAR_OLD_FORMAT, $archive, @marentries, @marfiles);
 
@@ -36,18 +35,25 @@ if (defined($ENV{"XZ"})) {
 else {
     if (system("xz --version > /dev/null 2>&1") != 0) {
         # Some of the Windows build systems have xz.exe in topsrcdir/xz/.
-        my $xzwinpath = abs_path(__FILE__);
+        my $xzwinpath = __FILE__;
         $xzwinpath = substr($xzwinpath, 0, rindex($xzwinpath, '/'));
         $xzwinpath = substr($xzwinpath, 0, rindex($xzwinpath, '/'));
         $xzwinpath = substr($xzwinpath, 0, rindex($xzwinpath, '/'));
-        $xzwinpath = $xzwinpath . "/xz/xz.exe";
-        if (-e $xzwinpath) {
-            $XZ = $xzwinpath;
+        my $xzwin = $xzwinpath . "/xz/xz.exe";
+        if (-e $xzwin) {
+            $XZ = $xzwin;
         }
         else {
-            # If the xz executable was not found fallback to trying to execute
-            # xz and follow the normal failure path if it isn't found.
-            $XZ = "xz";
+            $xzwinpath = substr($xzwinpath, 0, rindex($xzwinpath, '/'));
+            $xzwin = $xzwinpath . "/xz/xz.exe";
+            if (-e $xzwin) {
+                $XZ = $xzwin;
+            }
+            else {
+                # If the xz executable was not found fallback to trying to execute
+                # xz and follow the normal failure path if it isn't found.
+                $XZ = "xz";
+            }
         }
     }
     else {