not a very informative error message

[Matt Harbison]

On Fri, 07 Aug 2015 07:19:38 -0400, Neal Becker <ndbecker2 at gmail.com>  
wrote:

> $ hg id
> 1f8f96084e75+ (collision) tip
>
> $ hg cat -r 1f8f96084e75+ test_awgn.py > /dev/null
               01234567890123

> hg: parse error at 13: not a prefix: end

Since this isn't a valid revision or revset, all it can tell you is that  
the problem occurred at the 13th character.

I'm not sure what you are trying to do here.  The '+' on the end of the  
revision simply means that the working directory is dirty- it isn't part  
of the revision value.  So either you want the content of the committed  
file (use 1f8f96084e75) or you want the content in the uncommitted working  
directory.  The latter isn't implemented yet [1].

[1]  
https://mercurial.selenic.com/wiki/RevsetVirtualRevisionPlan#Status_of_commands