All loaders share importPromises

[justinbmeyer]

All loaders should not share importPromises. importPromises, like the modules registry should be unique to a given loader.

This bug exposes itself in the following scenario:

Creating multiple loaders and using them to load the same module, but have different fetch or normalize behavior:

loader1 = new Loader({ ... })
loader2 = new Loader({ ..., fetch: function(){  //different behavior  }  })

If loader1 and loader2 are used to import the same module at approximately the same time, loader2's fetch will not be called:

loader1.import('foo')
loader2.import('foo')

As far as I know, loader1 and loader2 should share nothing. Let me know if you agree and I can create a pull request moving importPromises onto _loader or somewhere else. Thanks!

[unscriptable]

👍

[guybedford]

Well caught - I've included a fix on master.