docchecker: remove naked except clause
This is fixing for 'naked except clause' check-code rule.
check-code has overlooked this, because a file isn't recognized as one
to be checked (this problem is fixed by subsequent patch).
to build a new macosx binary package:
install macpython from http://www.python.org/download/mac
install py2app from http://pythonmac.org/packages/
make sure /usr/local/bin is in your path
run bdist_mpkg in top-level hg directory
find packaged stuff in dist directory