Note when 13290 was introduced.

changes/bug13290-avoid-div-zero-circuitstatus-pareto

@@ -2,4 +2,4 @@
     - In circuit_build_times_calculate_timeout() in circuitstats.c, avoid
       dividing by zero in the pareto calculations. This traps under
       clang -fsanitize=undefined-trap -fsanitize-undefined-trap-on-error.
-      Fixes bug 13290.
+      Fixes bug 13290; bugfix on tor-0.2.2.2-alpha.