Selecting Date Causes Complete Lockup of Emacs

[Ian Barton <lists@wilkesley.net>]

+#begin_src
:SETUP:
#+DRAWERS: SETUP NOTES PROPERTIES
#+TITLE: Log of Various Bike Rides in 2014.
#+STARTUP: overview indent
#+STARTUP: hidestars
#+OPTIONS: H:3 num:2 tags:t toc:nil timestamps:t eX:t LaTeX:t
#+TAGS: n_wales(n) lakes(l) scotland(s) peak_district(p)
:END:

* January.
#+tblname: january

|------+---------------+-------|
| Date | Distance (km) | Notes |
|------+---------------+-------|
|      |               |       |
#+TBLFM: @>$2=vsum(@2..@-1)

+#end_src

Place the point in the Date column and type C-c !. Now select a date in 
the calendar. I chose a date in the past few days, but don't know if 
this is relevant. Emacs locks up completely, no back trace and the only 
way out is kill -9.

GNU Emacs 24.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.8.2)
  of 2013-08-06 on -mnt-storage-buildroots-staging-x86_64-eric

This has been happening for a while, so over several git updates. 
However, I haven't been able to reproduce the sequence of events causing 
the lockup until just now.

If anyone else can reproduce this I'll try and track down when it 
started happening. Otherwise I'll try bisecting my configuration.

Ian.