build-pspp: Use ^0 to really verify commit number.

If we specify a full commit number to "git rev-parse" then it doesn't
check whether that commit really exists.

diff --git a/build-pspp b/build-pspp
index 2fff2c853ec2cb693b7fb53c93e1edc5df056a83..d45a9efba7990d224d093790f0e8e7d51ff8969a 100755 (executable)
--- a/build-pspp
+++ b/build-pspp
@@ -235,7 +235,7 @@ EOF
       or die "rename $fullname.new to $fullname failed: $!\n";
 
     # If we don't already have that Gnulib commit, update Gnulib.
-    system ("$GIT rev-parse --verify --quiet $gnulib_commit > /dev/null");
+    system ("$GIT rev-parse --verify --quiet $gnulib_commit^0 > /dev/null");
     if ($? != 0) {
        start_step ("Updating Gnulib to obtain commit");
        run ("$GIT fetch gnulib");