cmd/go: loading dependencies with `go test -i` does not correctly handle `*.go` import paths [1.13 backport]

[gopherbot]

@Helcaraxan requested issue #34653 to be considered for backport to the next 1.13 minor release.

@gopherbot please backport to 1.13, this was a regression

[Helcaraxan]

As per @bcmills's comment here I'd suggest that we backport the fix for this issue, which is overlapping with already backported fix for #32483.

[bcmills]

This would be a companion to #34243, for which the backport has already been merged.

[gopherbot]

Change https://golang.org/cl/198957 mentions this issue: [release-branch.go1.13] cmd/go: fix listing of ambiguous paths

[gopherbot]

Closed by merging 2f73eed to release-branch.go1.13.