copies: extract value comparison in the python copy tracing
This mirror what we did in the Rust code. This is useful to prepare rework for
this comparison logic that we will need to handle more advanced chaining cases
(when merges are chained).
Differential Revision: https://phab.mercurial-scm.org/D9590
{
// 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)
}