upgrade: implement partial upgrade for upgrading persistent-nodemap
Upgrading repositories to use persistent nodemap should be fast and easy as it
requires only two things:
1) Updating the requirements
2) Writing a persistent-nodemap on disk
For both of the steps above, we don't need to edit existing revlogs.
This patch makes upgrade only do the above mentioned two steps if we are
only upgarding to use persistent-nodemap feature.
Since `nodemap.persist_nodemap()` assumes that there exists a nodemap file for
the given revlog if we are trying to call it, this patch adds `force` argument
to create a file if does not exist which is true in our upgrade case.
The test changes demonstrate that we no longer write nodemap files for manifest
after upgrade which I think is desirable.
Differential Revision: https://phab.mercurial-scm.org/D9936
{
// 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)
}