lib: drop "-2" flag for "py.exe" launcher

Now that node-gyp supports both Python 2 and Python 3,
We don't need to explicitly try to find only Python 2.

Fixes: #2130
Refs: https://docs.python.org/3/using/windows.html#launcher
PR-URL: #2131
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Rod Vagg <rod@vagg.org>

lib/find-python.js

@@ -119,7 +119,7 @@ PythonFinder.prototype = {
         checks.push({
           before: () => {
             this.addLog(
-              'checking if the py launcher can be used to find Python 2')
+              'checking if the py launcher can be used to find Python')
           },
           check: this.checkPyLauncher
         })
@@ -188,15 +188,10 @@ PythonFinder.prototype = {
   // Distributions of Python on Windows by default install with the "py.exe"
   // Python launcher which is more likely to exist than the Python executable
   // being in the $PATH.
-  // Because the Python launcher supports all versions of Python, we have to
-  // explicitly request a Python 2 version. This is done by supplying "-2" as
-  // the first command line argument. Since "py.exe -2" would be an invalid
-  // executable for "execFile", we have to use the launcher to figure out
-  // where the actual "python.exe" executable is located.
   checkPyLauncher: function checkPyLauncher (errorCallback) {
     this.log.verbose(
-      `- executing "${this.pyLauncher}" to get Python 2 executable path`)
-    this.run(this.pyLauncher, ['-2', ...this.argsExecutable], false,
+      `- executing "${this.pyLauncher}" to get Python executable path`)
+    this.run(this.pyLauncher, this.argsExecutable, false,
       function (err, execPath) {
       // Possible outcomes: same as checkCommand
         if (err) {

test/test-find-python.js

@@ -146,14 +146,13 @@ test('find python - no python2, no python, unix', function (t) {
 })
 
 test('find python - no python, use python launcher', function (t) {
-  t.plan(4)
+  t.plan(3)
 
   var f = new TestPythonFinder(null, done)
   f.win = true
 
   f.execFile = function (program, args, opts, cb) {
     if (program === 'py.exe') {
-      t.notEqual(args.indexOf('-2'), -1)
       t.notEqual(args.indexOf('-c'), -1)
       return cb(null, 'Z:\\snake.exe')
     }