symlinks: add basic symlink functions to util.py

symlinks: check whether a filesystem supports symlinks

exec: remove last flag from is_exec

exec: add execfunc to simplify exec flag support on non-exec filesystems

pull umask-checking up

exec: checkexec checks whether filesystem supports exec flags

expanded bash_completion for transplant extension

Yield entries from [paths], too, when completing -R/--repository.

Corrected synopsis for transplant.

Improved error message for extensions overriding commands (with test): - Old text "module foo overrides bar" was misread as overriding module bar. - Only print a single warning line per extension instead of one for each command.

sync with stable

Don't use -f for rm in tests where not needed. Drop /bin/ from /bin/rm.

test-manifest-merging: we only need to remove files

Make test-manifest-merging less likely to delete the whole filesystem

Send encoding information in rss header

Fix a pygettext complaint

spelling fix

mq: remove unecessary code, duplicate with util.opener

hgk: (re)optimize reading of changelog and manifest

mq: use contexts

hgk: use contexts

hgk: remove unused code, node2 is always set

extdiff: use contexts

bugzilla: use contexts, simplify

acl: use contexts

hgweb: fix unused import

hgweb: use contexts, fix coding style

commands.py: use contexts in various places (debug*state, revert)

cmdutil.py: use contexts in findrenames

commands.py: use contexts in export