- fix bug where we did not reject invalid classes like '[[:alpha'
- debloat while at it:
   text    data     bss     dec     hex filename
   1554       0      19    1573     625 tr.o.oorig
   1357       0      16    1373     55d tr.o
diff --git a/testsuite/tr/tr-d-alnum-works b/testsuite/tr/tr-d-alnum-works
new file mode 100644
index 0000000..d440f8f
--- /dev/null
+++ b/testsuite/tr/tr-d-alnum-works
@@ -0,0 +1,4 @@
+echo testing | tr -d '[[:alnum:]]' > logfile.gnu
+echo testing | busybox tr -d '[[:alnum:]]' > logfile.bb
+
+diff -u logfile.gnu logfile.bb