filecache: use try-except for faster __dict__ lookup
Python function call is slow, and the cost could be significant here.
$ hg perfrevset 'branch(tip)' -R mercurial
(orig) wall 0.139511 comb 0.140000 user 0.140000 sys 0.000000 (best of 66)
(this) wall 0.114195 comb 0.110000 user 0.110000 sys 0.000000 (best of 81)
# An example WSGI for use with mod_wsgi, edit as necessary
# See https://mercurial-scm.org/wiki/modwsgi for more information
# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"
# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")
# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()
# enable demandloading to reduce startup time
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb
application = hgweb(config)