status: handle more node indicators in buildstatus
There are several different node markers that indicate different working copy
states. The context._buildstatus function was only handling one of them, and
this patch makes it handle all of them (falling back to file content comparisons
when in one of these states).
This affects a future patch where we get rid of context._manifestmatches as part
of getting rid of manifest.matches(). context._manifestmatches is currently
hacky in that it uses the newnodeid for all added and modified files, which is
why the current newnodeid check is sufficient. When we get rid of this function
and use the normal manifest.diff function, we start to see the other indicators
in the nodes, so they need to be handled or else the tests fail.