imports: allow dirPackageInfo to be overridden
imports: allow dirPackageInfo to be overridden

Change-Id: Ie90d2681e364e2a3f905675db266cb8960e08277
Reviewed-on: https://go-review.googlesource.com/39995
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

syreclabs/go-tools,golang/tools,golang/tools,golang/tools,golang/tools,syreclabs/go-tools,syreclabs/go-tools,golang/tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools