A 'tweak' has been added to the beta to control the format of the publication date field. Once the change has been incorporated, you can control the format by editing the file tweaks.py. The folder containing the file can be opened by going to preferences/advanced and clicking 'open calibre configuration directory'.
Documentation is in {Calibre install directory}/resources.default_tweaks.py
What it says:
Code:
# Format to be used for publication date
# A string controlling how the publication date is displayed in the GUI
# d the day as number without a leading zero (1 to 31)
# dd the day as number with a leading zero (01 to 31)
# ddd the abbreviated localized day name (e.g. 'Mon' to 'Sun').
# dddd the long localized day name (e.g. 'Monday' to 'Qt::Sunday').
# M the month as number without a leading zero (1-12)
# MM the month as number with a leading zero (01-12)
# MMM the abbreviated localized month name (e.g. 'Jan' to 'Dec').
# MMMM the long localized month name (e.g. 'January' to 'December').
# yy the year as two digit number (00-99)
# yyyy the year as four digit number
# For example, given the date of 9 Jan 2010, the following formats show
# MMM yyyy ==> Jan 2010 yyyy ==> 2010 dd MMM yyyy ==> 09 Jan 2010
# MM/yyyy ==> 01/2010 d/M/yy ==> 9/1/10 yy ==> 10
# default if not set: MMM yyyy
gui_pubdate_display_format = 'MMM yyyy'