Losing first word of message with Markdown pre encoding

[wofka72]

UPD. See the comment below for real issue

=== Original issue text starts here ===

Context

• Operating System: Ubuntu 18.04
• Python Version: 3.8.0
• aiogram version: 2.9.2
• aiohttp version: 3.6.2
• uvloop version (if installed): Not installed

Expected Behavior

Message sended with parse_mode=ParseMode.MARKDOWN and wrapped with ```-braces loses first line (text till linebreak) if it have more than one line.

Current Behavior

First line should be sent too.

Steps to Reproduce

from aiogram import Bot
from aiogram.dispatcher import Dispatcher
from aiogram.types import ParseMode, Message
from aiogram.utils import executor

bot = Bot(token="<your_token>")
dp = Dispatcher(bot)

@dp.message_handler()
async def echo_message(msg: Message):
    await bot.send_message(msg.from_user.id, "```123\n456```", parse_mode=ParseMode.MARKDOWN)

executor.start_polling(dp)

loses first line:

async def echo_message(msg: Message):
    await bot.send_message(msg.from_user.id, "```123```", parse_mode=ParseMode.MARKDOWN)

works well:

Possible workaround before fix

1. Adding extra linebreak to the beginning of message.

await bot.send_message(msg.from_user.id, "```\n123\n456```", parse_mode=ParseMode.MARKDOWN)

2. Using HTML encoding.

await bot.send_message(msg.from_user.id, "<pre>123\n456</pre>", parse_mode=ParseMode.HTML)

[evgfilim1]

Hello and thanks for your report. However, it is upstream feature for specifying language in code block (like it is in GitHub).

Screenshot from Bot API documentation (picture is clickable):

[wofka72]

Method pre of aiogram.utils.text_decoration.MarkdownDecoration class just wraps text with tripple-quotes ```.
And sending such messages omits first word too.

from aiogram.utils.markdown import markdown_decoration as markdown  # use the object of class specified above
await bot.send_message(msg.from_user.id, markdown.pre("Answer: 42"), parse_mode=ParseMode.MARKDOWN)

I trapped little bit to this type of behaviour. I think that it could be strange and not obvious for new users. And on the other side it's small and some code could consider this behaviour. So I think that it shouldn't be changed on this stage of the project.
Just writing here about this feature :)

[evgfilim1]

And sending such messages omits first word too.

Oh, now it looks like a small bug in our side. I'll reopen this issue and update the description. Thanks for clarification, @wofka72.

[p82o]

label upstream can be removed because of #597