Incremental update of blocks with imports use the wrong paths

[mbostock]

Note the lack of _import here:

Example code is in foo.md:

import {bar} from "./bar.js";

display(bar);

[mbostock]

This has been a huge pain doing BI development. We should figure out how to write tests for the preview server…

[mbostock]

Okay, this is more interesting than I expected. The bug is that because we’re now using relative paths for imports (e.g., ./_import/foo.js), the import is computed relative to the client library /_observablehq/client.js not the page. That’s surprising!