Stage distribution in a separate process

lib/Zef/Client.rakumod

@@ -1087,13 +1087,31 @@ class Zef::Client {
                 });
                 my Str @includes = $staging-repo.path-spec;
                 $_.dist.metainfo<includes> = @includes;
-                $staging-repo.install($_.dist, :precompile($!precompile-install));
-                self.logger.emit({
-                    level   => INFO,
-                    stage   => STAGING,
-                    phase   => AFTER,
-                    message => "Staging [OK] for {$_.dist.identity}",
-                });
+
+                # Spawn a new process to run CompUnit::Repository::Staging.install(...) to ensure we have a clean slate.
+                # We turn the Zef::Distribution::Local into a Distribution::Hash so the new process doesn't need to have
+                # a repo path pointing to Zef::Distribution::Local.
+                my $bare-dist = Distribution::Hash.new($_.dist.meta, :prefix($_.dist.path.IO));
+                my $staged := try so Zef::zrun(:!out, :!err, :cwd($_.dist.path), $*EXECUTABLE, '-e', "{$staging-repo.raku}.install({$bare-dist.raku}, :precompile({$!precompile-install}))");
+
+                if $staged {
+                    self.logger.emit({
+                        level   => INFO,
+                        stage   => STAGING,
+                        phase   => AFTER,
+                        message => "Staging [OK] for {$_.dist.identity}",
+                    });
+                }
+                else {
+                    self.logger.emit({
+                        level   => ERROR,
+                        stage   => STAGING,
+                        phase   => AFTER,
+                        candi   => $_,
+                        message => "Staging [FAIL]: {$_.dist.?identity // $_.as} from {$_.uri}",
+                    });
+                    die("Aborting due to staging failure: {$_.dist.?identity // $_.uri}");
+                }
 
                 $_;
             });