### Please describe the problem.
Pairing over my local network doesn't work.  The pairing process never finishes.  The log shows that the same PairMsg messages are repeated endlessly.

### What steps will reproduce the problem?


### What version of git-annex are you using? On what operating system?
I'm on Ubuntu Raring 13.04.  I installed git-annex 4.20131024 from the Precise PPA.  It is working fine with a remote ssh repo, just not local pairing.

### 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
[2013-11-01 16:55:21 CDT] main: Pairing in progress
[2013-11-01 16:55:55 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"Onyx\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBT0Y6TTzTg8nWwonmgUPPwJmPIaJzfEoJl8DbuylpgXqGCQ4doJXuvBODHIehPfyMr1xCWqNlNNLkcWg/a/eHFceyt3IlcD9XaZ1aKPzPmpjYKKf5amiYd6mAssw8zFaZUvwaXkNuHZpXVZyg6C6TkT6kdfln+6fOJZpSGQzksy0jka/Rzx0KXjsp3oqO4tQJbC7AX0nvmD0zvLtyCURzfGV+n2IqQxpPf2nP75Evt8jamcuqm6pWoe+hj9zjGytIXpSKe35wzRwUAUrjgmZ9NweuWfi2uMPJlDv8/n+Q3HyjygA+GzixBGuYXDt1CD8ISZvuoygS+9+jeY9uYH8b me@Onyx\\n\", pairUUID = UUID \"834b4f39-ca66-4baf-9323-57ef7058d7d0\"},IPv4Addr 2281744576), verifiableDigest = \"8d5d380542f7377f09a4584a38b0dbcea9ea215c\"})"
[2013-11-01 16:55:56 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"kubbie\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCvBEWT+AiAmehOFyTQWlSdwDs7DDbkw7rfZ4W/IeG5awZjMgT5BefIv9cmar8vGIIEFMZLpf8cL3xIargDz0xE2wuqj5CLkdz+DKp5f2FGs11Ax/62DZr+eCiVtPnwijFw0Cz0wMRzkN93uedrvzP/KkNRcczgWh3aZqn8WxlkCia1fyykm/pP3W80MNkiJYX5vXpu1NCV5KLu+UXQzKhM2njOauJ3W5wsMvSl8faZIpEmKVCD3BMDDruxTIxggA3kt9GCGvIbPawy+fGOpp/j6pHqnX3GB2kkT47RIZKYEv99HuLyvea+oY5R11FsC2yYY3ujIdUU0fXnV8pvrqSv me@kubbie\\n\", pairUUID = UUID \"fd6a6858-76c9-4eea-b733-9359c7313e72\"},IPv4Addr 1879091392), verifiableDigest = \"cbd8197c3d78c8c68bb30f63aa974cd88dd0fb13\"})"
[2013-11-01 16:55:57 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"Onyx\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBT0Y6TTzTg8nWwonmgUPPwJmPIaJzfEoJl8DbuylpgXqGCQ4doJXuvBODHIehPfyMr1xCWqNlNNLkcWg/a/eHFceyt3IlcD9XaZ1aKPzPmpjYKKf5amiYd6mAssw8zFaZUvwaXkNuHZpXVZyg6C6TkT6kdfln+6fOJZpSGQzksy0jka/Rzx0KXjsp3oqO4tQJbC7AX0nvmD0zvLtyCURzfGV+n2IqQxpPf2nP75Evt8jamcuqm6pWoe+hj9zjGytIXpSKe35wzRwUAUrjgmZ9NweuWfi2uMPJlDv8/n+Q3HyjygA+GzixBGuYXDt1CD8ISZvuoygS+9+jeY9uYH8b me@Onyx\\n\", pairUUID = UUID \"834b4f39-ca66-4baf-9323-57ef7058d7d0\"},IPv4Addr 2281744576), verifiableDigest = \"8d5d380542f7377f09a4584a38b0dbcea9ea215c\"})"
[2013-11-01 16:55:58 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"kubbie\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCvBEWT+AiAmehOFyTQWlSdwDs7DDbkw7rfZ4W/IeG5awZjMgT5BefIv9cmar8vGIIEFMZLpf8cL3xIargDz0xE2wuqj5CLkdz+DKp5f2FGs11Ax/62DZr+eCiVtPnwijFw0Cz0wMRzkN93uedrvzP/KkNRcczgWh3aZqn8WxlkCia1fyykm/pP3W80MNkiJYX5vXpu1NCV5KLu+UXQzKhM2njOauJ3W5wsMvSl8faZIpEmKVCD3BMDDruxTIxggA3kt9GCGvIbPawy+fGOpp/j6pHqnX3GB2kkT47RIZKYEv99HuLyvea+oY5R11FsC2yYY3ujIdUU0fXnV8pvrqSv me@kubbie\\n\", pairUUID = UUID \"fd6a6858-76c9-4eea-b733-9359c7313e72\"},IPv4Addr 1879091392), verifiableDigest = \"cbd8197c3d78c8c68bb30f63aa974cd88dd0fb13\"})"
[2013-11-01 16:55:59 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"Onyx\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBT0Y6TTzTg8nWwonmgUPPwJmPIaJzfEoJl8DbuylpgXqGCQ4doJXuvBODHIehPfyMr1xCWqNlNNLkcWg/a/eHFceyt3IlcD9XaZ1aKPzPmpjYKKf5amiYd6mAssw8zFaZUvwaXkNuHZpXVZyg6C6TkT6kdfln+6fOJZpSGQzksy0jka/Rzx0KXjsp3oqO4tQJbC7AX0nvmD0zvLtyCURzfGV+n2IqQxpPf2nP75Evt8jamcuqm6pWoe+hj9zjGytIXpSKe35wzRwUAUrjgmZ9NweuWfi2uMPJlDv8/n+Q3HyjygA+GzixBGuYXDt1CD8ISZvuoygS+9+jeY9uYH8b me@Onyx\\n\", pairUUID = UUID \"834b4f39-ca66-4baf-9323-57ef7058d7d0\"},IPv4Addr 2281744576), verifiableDigest = \"8d5d380542f7377f09a4584a38b0dbcea9ea215c\"})"
[2013-11-01 16:56:00 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"kubbie\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCvBEWT+AiAmehOFyTQWlSdwDs7DDbkw7rfZ4W/IeG5awZjMgT5BefIv9cmar8vGIIEFMZLpf8cL3xIargDz0xE2wuqj5CLkdz+DKp5f2FGs11Ax/62DZr+eCiVtPnwijFw0Cz0wMRzkN93uedrvzP/KkNRcczgWh3aZqn8WxlkCia1fyykm/pP3W80MNkiJYX5vXpu1NCV5KLu+UXQzKhM2njOauJ3W5wsMvSl8faZIpEmKVCD3BMDDruxTIxggA3kt9GCGvIbPawy+fGOpp/j6pHqnX3GB2kkT47RIZKYEv99HuLyvea+oY5R11FsC2yYY3ujIdUU0fXnV8pvrqSv me@kubbie\\n\", pairUUID = UUID \"fd6a6858-76c9-4eea-b733-9359c7313e72\"},IPv4Addr 1879091392), verifiableDigest = \"cbd8197c3d78c8c68bb30f63aa974cd88dd0fb13\"})"
[2013-11-01 16:56:01 CDT] PairListener: received "PairMsg (Verifiable {verifiableVal = (PairReq,PairData {remoteHostName = Just \"Onyx\", remoteUserName = \"me\", remoteDirectory = \"~/annex\", remoteSshPubKey = \"ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBT0Y6TTzTg8nWwonmgUPPwJmPIaJzfEoJl8DbuylpgXqGCQ4doJXuvBODHIehPfyMr1xCWqNlNNLkcWg/a/eHFceyt3IlcD9XaZ1aKPzPmpjYKKf5amiYd6mAssw8zFaZUvwaXkNuHZpXVZyg6C6TkT6kdfln+6fOJZpSGQzksy0jka/Rzx0KXjsp3oqO4tQJbC7AX0nvmD0zvLtyCURzfGV+n2IqQxpPf2nP75Evt8jamcuqm6pWoe+hj9zjGytIXpSKe35wzRwUAUrjgmZ9NweuWfi2uMPJlDv8/n+Q3HyjygA+GzixBGuYXDt1CD8ISZvuoygS+9+jeY9uYH8b me@Onyx\\n\", pairUUID = UUID \"834b4f39-ca66-4baf-9323-57ef7058d7d0\"},IPv4Addr 2281744576), verifiableDigest = \"8d5d380542f7377f09a4584a38b0dbcea9ea215c\"})"
...and so on and so on...
# End of transcript or log.
"""]]

> I was able to reproduce something very like this by starting
> pairing separately on both computers under poor network conditions (ie,
> weak wifi on my front porch).
> 
> So, I've made a new PairReq message that has not been seen before 
> always make the alert pop up, even if the assistant thinks it is
> in the middle of its own pairing process (or even another pairing process
> with a different box on the LAN).
>
> (This shouldn't cause a rogue PairAck to disrupt a pairing process part
> way through.)
> 
> [[done]] --[[Joey]]