[MERGE] ``BZR_LOG=disable`` suppresses writing messages to .bzr.log.

[John Arbash Meinel]

Alexander Belchenko wrote:
> Bernhard Voelker пишет:
>> why not let the OS decide what to do with it?
>> I think
>>
>>         _bzr_log_filename = '/dev/null'
>>
>> is fully okay - every write to it will be automatically thrown
>> away by the kernel.
>>
>> With your solution, we'd make '/dev/null' and 'NUL' magic words,
>> but from OS side they aren't! They're just character devices handled 
>> by a device driver, in this case the sink.
> 
> May be you're right. I'll test it on Windows and then bb:resubmit.
> 
> 

Well, there is a small performance difference. Since in one case we 
don't do any work that just gets sent to the deep blue yonder.

I'm guessing it may be reasonable to not worry about it, though.

John
=:->