Short-circuit check --rerun if testdir doesn't exist

CHANGELOG.md

@@ -10,6 +10,9 @@ this project uses date-based 'snapshot' version identifiers.
 ### Changed
 - Document default value of `ctanpkg` as a valid lua expression
 
+### Fixed
+- Short-circuit `check --rerun` if `testdir` doesn't exist
+
 ## [2023-11-01]
 
 ### Changed

l3build-check.lua

@@ -926,7 +926,14 @@ end
 function check(names)
   local errorlevel = 0
   if testfiledir ~= "" and direxists(testfiledir) then
-    if not options["rerun"] then
+    if options["rerun"] then
+      -- direxists() returns a boolean, not integer
+      errorlevel = direxists(testdir) and 0 or 1
+      if errorlevel ~= 0 then
+        print("\n  Test directory \"" .. testdir .. "\" doesn't exist. Try again without \"--rerun\".\n")
+        return errorlevel
+      end
+    else
       errorlevel = checkinit()
       if errorlevel ~= 0 then
         return errorlevel