[itchat] Download multiple files in batch will produce duplicated contents

[blueset]

Fix: Update code in itchat/components/messages.py

        elif m['MsgType'] == 49: # sharing
            if m['AppMsgType'] == 6:
                rawMsg = m
                cookiesList = {name:data for name,data in core.s.cookies.items()}
                url = core.loginInfo['fileUrl'] + '/webwxgetmedia'
                params = {
                    'sender': rawMsg['FromUserName'],
                    'mediaid': rawMsg['MediaId'],
                    'filename': rawMsg['FileName'],
                    'fromuser': core.loginInfo['wxuin'],
                    'pass_ticket': 'undefined',
                    'webwx_data_ticket': cookiesList['webwx_data_ticket'],}
                headers = { 'User-Agent' : config.USER_AGENT }
                def download_atta(attaDir=None):
                    r = core.s.get(url, params=params, stream=True, headers=headers)
                    tempStorage = io.BytesIO()
                    for block in r.iter_content(1024):
                        tempStorage.write(block)
                    if attaDir is None:
                        return tempStorage.getvalue()
                    with open(attaDir, 'wb') as f:
                        f.write(tempStorage.getvalue())
                    return ReturnValue({'BaseResponse': {
                        'ErrMsg': 'Successfully downloaded',
                        'Ret': 0, }})
                msg = {
                    'Type': 'Attachment',
                    'Text': download_atta, }