import-checker: make imported_modules yield absolute dotted_name_of_path This patch makes `imported_modules()` always yield absolute `dotted_name_of_path()`-ed name by strict detection with `fromlocal()`. This change improves circular detection in some points: - locally defined modules, of which name collides against one of standard library, can be examined correctly For example, circular import related to `commands` is overlooked before this patch. - names not useful for circular detection are ignored Names below are also yielded before this patch: - module names of standard library (= not locally defined one) - non-module names (e.g. `node.nullid` of `from node import nullid`) These redundant names decrease performance of circular detection. For example, with files at 1ef96a3b8b89, average loops per file in `checkmod()` is reduced from 165 to 109. - `__init__` can be handled correctly in `checkmod()` For example, current implementation has problems below: - `from xxx import yyy` doesn't recognize `xxx.__init__` as imported - `xxx.__init__` imported via `import xxx` is treated as `xxx`, and circular detection is aborted, because `key` of such module name is not `xxx` but `xxx.__init__` - it is easy to enhance for `from . import xxx` style or so (in the future) Module name detection in `imported_modules()` can use information in `ast.ImportFrom` fully. It is assumed that all locally defined modules are correctly specified to `import-checker.py` at once. Strictly speaking, when `from foo.bar.baz import module1` imports `foo.bar.baz.module1` module, current `imported_modules()` yields only `foo.bar.baz.__init__`, even though also `foo.__init__` and `foo.bar.__init__` should be yielded to detect circular import exactly. But this limitation is reasonable one for improvement in this patch, because current `__init__` files in Mercurial seems to be implemented carefully.