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.