Errbot doesn't treat new lines as command seperators

[sinkingpoint]

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I am...

• Reporting a bug
• Suggesting a new feature
• Requesting help with running my bot
• Requesting help writing plugins
• Here about something else

I am running...

• Errbot version:

nobody@box:/$ errbot --version
Errbot version 5.2.0

• OS version: Debian 9.5
• Python version: Python 3.6.5
• Using a virtual environment: yes

Issue description

When scanning for a command to run, errbot splits the command by spaces (https://github.com/errbotio/errbot/blob/master/errbot/core.py#L269). In the event that a message has been sent with a newline separating the command from the arguments, this fails and errbot (IMO) incorrectly identifies the command as not found.

Steps to reproduce

Consider the following bot command:

@botcmd
def hello(self, msg, args):
  return 'Hello! You said: ' + args

When called as such:

@errbot hello
Line 1

In this case, errbot looks for commands: ["hello\nline_1", "hello\nline"] - as it does not treat the \n as a whitespace character, it does not attempt to look for a command 'hello', and thus fails the command lookup. What I would expect is that errbot correctly calls the hello function with the argument 'Line1' (Correctly trimming the whitespace)

Additional info

If you have any more information, please specify it here.

[sijis]

Closed via #1496.