crecord: call prevsibling() and nextsibling() directly The 3 classes for items used in crecord (uiheader, uihunk, uihunkline) all have prevsibling() and nextsibling() methods. The two methods are used to get the previous/next item of the same type of the same parent element as the current one: when `a` is a uihunkline instance, a.nextsibling() returns the next line in this hunk (or None, if `a` is the last line). There are also two similar methods: previtem() and nextitem(). When called with constrainlevel=True (the default) they simply returned the result of prevsibling()/nextsibling(). Only when called with constrainlevel=False they did something different: they returned previous/next item regardless of its type (so if `a` is the last line in a hunk, a.nextitem(constrainlevel=False) could return the next hunk or the next file -- something that is not a line). Let's simplify this logic and make code call -sibling() methods when only siblings are needed and -item() methods when any item would do, and then remove the constrainlevel argument from previtem() and nextitem().

#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also https://mercurial-scm.org/wiki/PublishingRepositories

# 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()

from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)