tags: don't crash if unable to write tag cache
This happens with hgweb in real life, if the httpd user is unable to
write in the repository directory. Another case is doing 'hg incoming'
on a repository in the filesystem owned by someone else.
syntax: glob
*.elc
*.orig
*.rej
*~
*.mergebackup
*.o
*.so
*.pyd
*.pyc
*.swp
*.prof
\#*\#
.\#*
tests/.coverage*
tests/annotated
tests/*.err
build
contrib/hgsh/hgsh
dist
doc/*.[0-9]
doc/*.[0-9].gendoc.txt
doc/*.[0-9].{x,ht}ml
MANIFEST
patches
mercurial/__version__.py
Output/Mercurial-*.exe
.DS_Store
tags
cscope.*
i18n/hg.pot
locale/*/LC_MESSAGES/hg.mo
# files installed with a local --pure build
mercurial/base85.py
mercurial/bdiff.py
mercurial/diffhelpers.py
mercurial/mpatch.py
mercurial/osutil.py
mercurial/parsers.py
syntax: regexp
^\.pc/
^\.(pydev)?project