test/run: fixed OS X (where os.getenv("OS") returns nil)

diff --git a/src/tests/run.mlua b/src/tests/run.mlua
index e6003a6915ce385cdbf7306220dc7c4925383a4e..de91738cd2621b6e583962dda478f7e34a3a7be1 100644 (file)
--- a/src/tests/run.mlua
+++ b/src/tests/run.mlua
@@ -3,7 +3,7 @@
 
 -{ extension 'xloop' }
 
-ls = io.popen (os.getenv "OS" :match "^Windows" and "dir /b" or "ls")
+ls = io.popen ( (os.getenv("OS") or "") :match "^Windows" and "dir /b" or "ls")
 this_script = arg[1]
 
 for filename in ls :lines() if filename ~= this_script and filename :strmatch  "%.m?lua$" do