support RUBY_ON_BUG envval on assert failure.

Check RUBY_ON_BUG env val also on rb_assert_failure().

error.c

@@ -580,17 +580,6 @@ bug_report_begin_valist(FILE *out, const char *fmt, va_list args)
     snprintf(buf, sizeof(buf), "\n%s\n\n", ruby_description);
     fputs(buf, out);
     preface_dump(out);
-
-#if RUBY_DEVEL
-    const char *cmd = getenv("RUBY_ON_BUG");
-    if (cmd) {
-        snprintf(buf, sizeof(buf), "%s %"PRI_PIDT_PREFIX"d", cmd, getpid());
-        int r = system(buf);
-        if (r == -1) {
-            snprintf(buf, sizeof(buf), "Launching RUBY_ON_BUG command failed.");
-        }
-    }
-#endif
 }
 
 #define bug_report_begin(out, fmt) do { \

vm_dump.c

@@ -925,6 +925,18 @@ rb_dump_machine_register(const ucontext_t *ctx)
 void
 rb_vm_bugreport(const void *ctx)
 {
+#if RUBY_DEVEL
+    const char *cmd = getenv("RUBY_ON_BUG");
+    if (cmd) {
+        char buf[0x100];
+        snprintf(buf, sizeof(buf), "%s %"PRI_PIDT_PREFIX"d", cmd, getpid());
+        int r = system(buf);
+        if (r == -1) {
+            snprintf(buf, sizeof(buf), "Launching RUBY_ON_BUG command failed.");
+        }
+    }
+#endif
+
 #ifdef __linux__
 # define PROC_MAPS_NAME "/proc/self/maps"
 #endif