waf: add support for subprocess.run for python2

wscript

@@ -17,6 +17,48 @@ import boards
 from waflib import Build, ConfigSet, Configure, Context, Utils
 from waflib.Configure import conf
 
+# Ref: https://stackoverflow.com/questions/40590192/getting-an-error-attributeerror-module-object-has-no-attribute-run-while
+try:
+    from subprocess import CompletedProcess
+except ImportError:
+    # Python 2
+    class CompletedProcess:
+
+        def __init__(self, args, returncode, stdout=None, stderr=None):
+            self.args = args
+            self.returncode = returncode
+            self.stdout = stdout
+            self.stderr = stderr
+
+        def check_returncode(self):
+            if self.returncode != 0:
+                err = subprocess.CalledProcessError(self.returncode, self.args, output=self.stdout)
+                raise err
+            return self.returncode
+
+    def sp_run(*popenargs, **kwargs):
+        input = kwargs.pop("input", None)
+        check = kwargs.pop("handle", False)
+        if input is not None:
+            if 'stdin' in kwargs:
+                raise ValueError('stdin and input arguments may not both be used.')
+            kwargs['stdin'] = subprocess.PIPE
+        process = subprocess.Popen(*popenargs, **kwargs)
+        try:
+            outs, errs = process.communicate(input)
+        except:
+            process.kill()
+            process.wait()
+            raise
+        returncode = process.poll()
+        if check and returncode:
+            raise subprocess.CalledProcessError(returncode, popenargs, output=outs)
+        return CompletedProcess(popenargs, returncode, stdout=outs, stderr=errs)
+
+    subprocess.run = sp_run
+    # ^ This monkey patch allows it work on Python 2 or 3 the same way
+
+
 # TODO: implement a command 'waf help' that shows the basic tasks a
 # developer might want to do: e.g. how to configure a board, compile a
 # vehicle, compile all the examples, add a new example. Should fit in