If UglyURLs = True, Hugo version 0.15 produced broken links to the category and tag pages. This Python 3 script moves and renames the category and tag index files, so that for these pages, we're pretending the UglyURLs=False.

patchBrokenHugoCategoryandTagLinks.py

# Currently the Hugo Static Site Generator (v0.15)
#   http://gohugio.io
# doesn't get the category and tag links correct if the
# uglyurls option is set in the config file ( "uglyurls=true"
#
# The generated site has category and tag links that point to a
# directory rather than the html file, but the directory doesn't
# contain an index.html file so the user ends up with a blank
# screen.
#
# e.g.
# /categories/linux       (which contains only an .xml file)
#    instead of
# /categories/linux.html
#
# This program moves and renames the file, like this:
#
#   /categories/linux.html --> /categories/linux/index.html
#
# and similarly for all categories and tags.
# So, after generating the site, just run this program from
# the hugo directory.
#
# It's a hack, but it'll do until the Hugo maintainers (who are
# doing a great job :-) get around the fixing the bug.
#
# Licence - BSD

import os, os.path, sys

def moveAndRenameIndex(pathname):
    dir, indexFilename = os.path.split(pathname)
    indexDir, ext = os.path.splitext(pathname)
    newName = os.path.join(indexDir, "index.html")

    try:
        os.rename(pathname, newName)
        print("Moved %s\n\t%s" %( pathname, newName) )
    except:
        print("Failed to relocate:", pathname)

#======================================================
# Main starts here

# If a root directory is specified use it else current directory
try:
   hugoRoot = sys.argv[1]
except:
    hugoRoot = os.getcwd()


publicDir = os.path.join(hugoRoot, "public")
if not os.path.isdir(publicDir):
    print("can't find public directory:", publicDir)
    sys.exit(1)


for whichDir in ['categories', 'tags']:
    path = os.path.join(hugoRoot, "public", whichDir)
    toMove = [os.path.join(path, f)
                 for f in os.listdir(path)
                     if f.endswith('.html') and
                     f != "index.html" and f != '.html' ]
    for f in toMove:
        moveAndRenameIndex(f)