If win_get_environment_variable fails due to win32api module not being present, gracefully fail out. Recognise MINGW64 as an MSYSTEM, and behave like MSYS even when MSYSTEM is set, but is of another flavor. (even when untested)

emsdk

@@ -40,9 +40,8 @@ if os.name == 'nt' or (os.getenv('SYSTEMROOT') != None and 'WINDOWS' in os.geten
 
 MSYS = False
 if os.getenv('MSYSTEM'):
-  if os.getenv('MSYSTEM') == 'MSYS':
-    MSYS = True
-  else:
+  MSYS = True
+  if os.getenv('MSYSTEM') != 'MSYS' and os.getenv('MSYSTEM') != 'MINGW64':
     print('Warning: MSYSTEM environment variable is present, and is set to "' + os.getenv('MSYSTEM') + '". This shell has not been tested with emsdk and may not work.') # https://stackoverflow.com/questions/37460073/msys-vs-mingw-internal-environment-variables
 
 OSX = False
@@ -219,7 +218,10 @@ def win_get_environment_variable(key, system=True):
     if e[0] != 2: # 'The system cannot find the file specified.'
       print('Failed to read environment variable ' + key + ':', file=sys.stderr)
       print(str(e), file=sys.stderr)
-    win32api.RegCloseKey(folder)
+    try:
+      win32api.RegCloseKey(folder)
+    except Exception as e:
+      pass
     os.environ['PATH'] = prev_path
     return None
   win32api.RegCloseKey(folder)