I've attached a paper I've written for the upcoming Denver SG15 meeting and
the Belfast meeting.

Abstract:
The changes to import in [P1703r1] were both too much and not enough to
enable fast dependency scanning via partial preprocessing. It made import
at the start of a line anywhere in the program an import-keyword, breaking
things like import->doImport();. Also, no similar changes were applied to
module. This paper fine-tunes the context-sensitivity of import and module,
applying the fixes discussed on the reflector.

- Michael Spencer