largefiles: adapt verify to batched remote statlfile (
issue3780)
9e1616307c4c introduced batching of statlfile, but not all codepaths got
converted.
'hg verify' with a remotestore could thus crash with
TypeError: 'builtin_function_or_method' object is not iterable
Also, the 'hash' variable was used without assigning to it. Don't use variable
names that collide with Python built-in functions. Instead we use 'expecthash'
as in localstore.
The tests for this issue covers an untested area. The tests happens to also
reveal incorrect attempts at getting non-existing largefiles, bad server side
handling of that, and corruption issues - all to be fixed later.