check python before announcing it doesn't exist

Author: kripken

tools/shared.py

@@ -529,8 +529,11 @@ def check_sanity(force=False):
         sys.exit(1)
 
     if not os.path.exists(PYTHON) and not os.path.exists(cmd + '.exe'):
-      logging.critical('Cannot find %s, check the paths in %s' % (PYTHON, EM_CONFIG))
-      sys.exit(1)
+      try:
+        subprocess.check_call([PYTHON, '--version'], stdout=PIPE, stderr=PIPE)
+      except:
+        logging.critical('Cannot find %s, check the paths in %s' % (PYTHON, EM_CONFIG))
+        sys.exit(1)
 
     if not fastcomp_ok:
       logging.critical('failing sanity checks due to previous fastcomp failure')