Fix REPL breakage from last commit

Need to explicitly stringify DepSpec if we gonna .contains it.

REPL testing routines explicitly request the `none` REPL line
editor, so the exploding logic that tries to figure out line
editor to use was never exercised.

src/core/REPL.pm6

@@ -180,7 +180,7 @@ do {
                 CATCH {
                     when {
                         $_ ~~ X::CompUnit::UnsatisfiedDependency
-                        and .specification.contains: $module-name
+                        and .specification.Str.contains: $module-name
                     } {
                         # ignore it
                     }

t/02-rakudo/repl.t

@@ -3,7 +3,7 @@ use lib <t/packages>;
 use Test;
 use Test::Helpers;
 
-plan 41;
+plan 42;
 
 my $*REPL-SCRUBBER = -> $_ is copy {
     s/^^ "You may want to `zef install Readline` or `zef install Linenoise`"
@@ -15,6 +15,16 @@ my $*REPL-SCRUBBER = -> $_ is copy {
     $_
 }
 
+subtest 'sanity check; load without tweaking line editor' => {
+    plan 3;
+    my $p := run $*EXECUTABLE, '--repl-mode=interactive', :in, :out, :err;
+    $p.in.say: '133742.flip.say';
+    $p.in.close;
+    like $p.out.slurp(:close),     /247331/, 'result of code is on STDOUT';
+    is $p.err.slurp(:close).chars, 0,        'no STDERR output';
+    is $p.exitcode,                0,        'successful exit code';
+}
+
 # RT #123187
 is-run-repl «'my int $t=4; $t.say;'  '$t.say'», <4 4>,
     'can use native typed variable on subsequent lines (1)';