Tweak legacy builder logic

This works with (and without) the candidates PRs in rakudo,
and without temporarily rewriting a meta file (to write in
Build.pm to provides). Not sure why this has to be done in
such a specific way, but it suffices to say that "it just
needs to be this way for now", where "for now" is such a time
or soluton that works for installing both Inline::Perl5 and
Linenoise.

META6.json

@@ -1,7 +1,7 @@
 {
     "perl"        : "6",
     "name"        : "zef",
-    "version"     : "0.1.31",
+    "version"     : "0.1.32",
     "auth"        : "github:ugexe",
     "description" : "It's like [cpanm] wearing high heels with a tracksuit",
     "license"     : "Artistic-2.0",

lib/Zef/Service/Shell/Build.pm6

@@ -1,5 +1,4 @@
 use Zef;
-use Zef::Utils::FileSystem;
 
 class Zef::Service::Shell::Build does Builder does Messenger {
     method build-matcher($path) { $path.IO.child("Build.pm").e }
@@ -11,57 +10,22 @@ class Zef::Service::Shell::Build does Builder does Messenger {
     # all the existing distributions using Build.pm
     method build($path, :@includes) {
         die "path does not exist: {$path}" unless $path.IO.e;
-        my $build-file = list-paths($path, :!r, :f, :!d).first({.basename eq 'Build.pm'});
 
-        my $json-ext = $path.IO.child('META6.json').e;
-        my Str $comp-version = ~$*PERL.compiler.version;
-        my $meta-name-workaround = $comp-version.substr(5..6) <= 5
-                                && $comp-version.substr(0..3) <= 2016
-                                && $json-ext;
+        # make sure to use -Ilib instead of -I. or else Linenoise's Build.pm will trigger a strange precomp error
+        my $build-file = $path.IO.child("Build.pm").absolute;
+        my $cmd        = "require '$build-file'; ::('Build').new.build('$path.IO.absolute()') ?? exit(0) !! exit(1);";
+        my @exec       = |($*EXECUTABLE, '-Ilib', |@includes.grep(*.defined).map({ "-I{$_}" }), '-e', "$cmd");
 
-        my $orig-result = legacy-build($path, :@includes, :$.stderr, :$.stdout);
-        return $orig-result if ?$orig-result;
+        $.stdout.emit("Command: {@exec.join(' ')}");
 
-        # Workaround rakudo CUR::FS bug when distribution has a
-        # Build.pm file, is using META6.json (not META.info), and
-        # the rakudo version is < 2016.05
-        # Retries try-legacy-hook after adding 'Build' => 'Build.pm' to provides
-        if $meta-name-workaround {
-            my $meta6-path     = $path.IO.child('META6.json');
-            my $meta6-bak      = $meta6-path.absolute ~ '.bak';
-            my $meta6-contents = $meta6-path.IO.slurp;
-            try move $meta6-path, $meta6-bak;
-            my %meta6 = from-json($meta6-contents);
-            %meta6<provides><Build> = 'Build.pm';
-            "{$meta6-path}".IO.spurt( to-json(%meta6) );
-            my $result = legacy-build($path, :@includes, :$.stderr, :$.stdout);
-            try unlink $meta6-path;
-            try move $meta6-bak, $meta6-path;
-            $result;
+        my $ENV := %*ENV;
+        my $passed;
+        react {
+            my $proc = zrun-async(@exec);
+            whenever $proc.stdout.lines { $.stdout.emit($_) }
+            whenever $proc.stderr.lines { $.stderr.emit($_) }
+            whenever $proc.start(:$ENV, :cwd($path)) { $passed = $_.so }
         }
+        return $passed;
     }
 }
-
-my sub legacy-build($path, :@includes, :$stderr, :$stdout) {
-    my $DEBUG = ?%*ENV<ZEF_BUILDPM_DEBUG>;
-
-    # Rakudo bug related to using path instead of module name
-    # my $cmd = "require <{$builder-path.basename}>; ::('Build').new.build('{$path.IO.absolute}'); exit(0);";
-    my $cmd = "::('Build').new.build('{$path.IO.absolute}'); exit(0);";
-
-    # see: https://github.com/ugexe/zef/issues/93
-    # my @exec = |($*EXECUTABLE, '-Ilib', '-I.', |@cl-includes, '-e', "$cmd");
-    my @exec = |($*EXECUTABLE, '-Ilib', '-I.', '-MBuild', |@includes.grep(*.defined).map({ "-I{$_}" }), '-e', "$cmd");
-
-    $stdout.emit("Command: {@exec.join(' ')}") if $DEBUG;
-
-    my $ENV := %*ENV;
-    my $passed;
-    react {
-        my $proc = zrun-async(@exec);
-        whenever $proc.stdout.lines { $stdout.emit($_) }
-        whenever $proc.stderr.lines { $stderr.emit($_) }
-        whenever $proc.start(:$ENV, :cwd($path)) { $passed = $_.so }
-    }
-    return $passed;
-}