git-cvsserver: typo in a comment: bas -> has

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-cvsserver.perl

@@ -2656,7 +2656,7 @@ sub descramble
     );
     my ($str) = @_;
 
-    # This should never happen, the same password format (A) bas been
+    # This should never happen, the same password format (A) has been
     # used by CVS since the beginning of time
     die "invalid password format $1" unless substr($str, 0, 1) eq 'A';