### Please describe the problem.


some time ago i was using the webapp bound to a dedicated port number to get around firewall reconfig. Now after some time without using the webapp i'm using it again and when i start it with 

     git-annex webapp --listen=192.168.21.12:46199

it never starts but just keeps waiting forever(?) 

Update:(to clarify - the following works fine but results in the "random" port "problem")

    git-annex webapp --listen=192.168.21.12




### What steps will reproduce the problem?


git-annex webapp --listen=192.168.21.12:46199


### What version of git-annex are you using? On what operating system?


version 5.20140716-g8c14ba8 on debian wheezy using your pre build static tar archive. 

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log


the log output is the following 3 lines 

[2014-07-23 16:41:45 CEST] main: starting assistant version 5.20140716-g8c14ba8
WebApp crashed: getAddrInfo: does not exist (Name or service not known)
[2014-07-23 16:41:45 CEST] WebApp: warning WebApp crashed: getAddrInfo: does not exist (Name or service not known)



# End of transcript or log.
"""]]
