Avoid a parallel make race condition where we load a half-copied module.

1 files changed, 4 insertions, 1 deletions

diff --git a/make_ext.pl b/make_ext.pl
index b5966a9e9f..f88c208046 100644
--- a/make_ext.pl
+++ b/make_ext.pl
@@ -231,8 +231,11 @@ sub build_extension {
     $perl ||= "$up/miniperl";
     my $return_dir = $up;
     my $lib_dir = "$up/lib";
+    # $lib_dir must be last, as we're copying files into it, and in a parallel
+    # make there's a race condition if one process tries to open a module that
+    # another process has half-written.
     $ENV{PERL5LIB}
-	= join $Config{path_sep}, $lib_dir, map {"$up/$_"} @toolchain;
+	= join $Config{path_sep}, (map {"$up/$_"} @toolchain), $lib_dir;
 
     unless (chdir "$ext_dir") {
 	warn "Cannot cd to $ext_dir: $!";