A <precheck> command is considered to have failed if it returns a non-zero

return code.  This way, if the precheck command can't be run at all for
whatever reason, it's treated as a precheck failure which causes the
test to be skipped.

tests/runtests.pl

@@ -486,6 +486,7 @@ sub torture {
         else {
             $ret = runclient($testcmd);
         }
+        #logmsg "$_ Returned " . $ret / 256 . "\n";
 
         # Now clear the variable again
         $ENV{'CURL_MEMLIMIT'} = undef;
@@ -1857,6 +1858,8 @@ sub singletest {
             if($o[0]) {
                 $why = $o[0];
                 chomp $why;
+            } elsif($?) {
+                $why = "precheck command error";
             }
             logmsg "prechecked $cmd\n" if($verbose);
         }