Convey remote backtrace if available in workitem

[iamer]

Depends on
jmettraux/ruote@b7eeff0

If the remote participant has set a trace in the workitem, add it to the error.

[jmettraux]

Hello,

thanks for the request.

This code will fail if err is not a hash...

OK, let me pull it in and add a test and fix it.

[iamer]

I did that similar to https://github.com/kennethkalmer/ruote-amqp/blob/master/lib/ruote/amqp/receiver.rb#L148 , wouldn't make sense to have a trace in h without an error.

It might be originally done like that so as not to reuse the error in case workitem gets resent (expression is reapplied for example ).

[jmettraux]

if there is no h['trace'] and err is a not a Hash then your code will raise on err['trace'].

Correction "string"['trace'] will not raise though....

1.9.3p194 :001 > "string"['trace']
 => nil
1.9.3p194 :002 >

[jmettraux]

ok, the pull request breaks the specs.

**err**
#<TypeError: can't convert String into Integer>
/Users/jmettraux/w/ruote-amqp/lib/ruote/amqp/receiver.rb:159:in `[]'
...

fixing...