dummyssh: call python script with python

We don't want windows to grab whatever python got configured to run .py file. We
need the python used during the test to be used.

Differential Revision: https://phab.mercurial-scm.org/D11083

tests/dummyssh

@@ -3,6 +3,7 b''
 from __future__ import absolute_import
 
 import os
+import shlex
 import subprocess
 import sys
 
@@ -23,5 +24,12 b' hgcmd = sys.argv[2]'
 if os.name == 'nt':
     # hack to make simple unix single quote quoting work on windows
     hgcmd = hgcmd.replace("'", '"')
+    cmds = shlex.split(hgcmd)
+    if cmds[0].endswith('.py'):
+        python_exe = os.environ['PYTHON']
+        cmds.insert(0, python_exe)
+    hgcmd = shlex.join(cmds)
+    # shlex generate windows incompatible string...
+    hgcmd = hgcmd.replace("'", '"')
 r = subprocess.call(hgcmd, shell=True)
 sys.exit(bool(r))