Fix regression with see'ing gensyms

basis/see/see-tests.factor

@@ -1,5 +1,5 @@
 IN: see.tests
-USING: see tools.test io.streams.string math ;
+USING: see tools.test io.streams.string math words ;
 
 CONSTANT: test-const 10
 [ "IN: see.tests\nCONSTANT: test-const 10 inline\n" ]
@@ -9,3 +9,5 @@ ALIAS: test-alias +
 
 [ "USING: math ;\nIN: see.tests\nALIAS: test-alias + inline\n" ]
 [ [ \ test-alias see ] with-string-writer ] unit-test
+
+[ ] [ gensym see ] unit-test

basis/see/see.factor

@@ -44,7 +44,7 @@ M: word print-stack-effect? drop t ;
 <PRIVATE
 
 : seeing-word ( word -- )
-    vocabulary>> vocab pprinter-in set ;
+    vocabulary>> dup [ vocab ] when pprinter-in set ;
 
 : word-synopsis ( word -- )
     {