child_process_uv: fix simple/test-child-process-cwd

Makefile

@@ -237,6 +237,7 @@ UVTEST += simple/test-tls-set-encoding
 UVTEST += simple/test-child-process-exit-code
 UVTEST += simple/test-child-process-buffering
 UVTEST += simple/test-child-process-exec-cwd
+UVTEST += simple/test-child-process-cwd
 
 
 test-uv: all

src/process_wrap.cc

@@ -107,8 +107,10 @@ class ProcessWrap : public HandleWrap {
     Local<Value> cwd_v = js_options->Get(String::New("cwd"));
     if (!cwd_v.IsEmpty() && cwd_v->IsString()) {
       String::Utf8Value cwd(cwd_v->ToString());
+      if (cwd.length() > 0) {
         options.cwd = strdup(*cwd);
       }
+    }
 
     // options.env
     Local<Value> env_v = js_options->Get(String::New("env"));