tags: don't read .hgtags fnodes from tags cache files Now that we have a standalone and shared cache for .hgtags fnodes, the .hgtags fnodes stored in the tags cache files are redundant. Upcoming patches will change the format of the tags cache files to remove this data and to improve the validation. To prepare for this, we change the tags reading code to ignore all but the tip .hgtags fnodes entries in existing tags cache files. All fnodes lookups now go through our new shared cache, which is why test output changed. Format of tags cache files has not yet changed.