msi: Any value of WindowsInstaller besides 0 means the product is installed.

dlls/msi/msi.c

@@ -799,17 +799,11 @@ INSTALLSTATE WINAPI MsiQueryProductStateW(LPCWSTR szProduct)
     if (rc != ERROR_SUCCESS)
         goto end;
 
-    switch (state)
-    {
-    case 1:
-        /* default */
+    if (state)
         state = INSTALLSTATE_DEFAULT;
-        break;
-    default:
-        FIXME("Unknown install state read from registry (%i)\n",state);
+    else
         state = INSTALLSTATE_UNKNOWN;
-        break;
-    }
+
 end:
     RegCloseKey(props);
     RegCloseKey(hkey);

dlls/msi/tests/msi.c

@@ -427,6 +427,14 @@ static void test_MsiQueryProductState(void)
     state = MsiQueryProductStateA(prodcode);
     ok(state == INSTALLSTATE_DEFAULT, "Expected INSTALLSTATE_DEFAULT, got %d\n", state);
 
+    data = 2;
+    res = RegSetValueExA(props, "WindowsInstaller", 0, REG_DWORD, (const BYTE *)&data, sizeof(DWORD));
+    ok(res == ERROR_SUCCESS, "Expected ERROR_SUCCESS, got %d\n", res);
+
+    /* WindowsInstaller value is not 1 */
+    state = MsiQueryProductStateA(prodcode);
+    ok(state == INSTALLSTATE_DEFAULT, "Expected INSTALLSTATE_DEFAULT, got %d\n", state);
+
     RegDeleteKeyA(userkey, "");
 
     /* user product key does not exist */