rhg: implement checkexec to support weird filesystems
In particular, some of our repos are stored on a fileserver that simulates
POSIX permissions poorly, in such a way that prevents the removal
of execute permission.
This causes rhg show a spurious unclean status, even though python
hg reports the repo as clean.
We fix this by making rhg implement the ~same checkexec logic
that python hg does.
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}