cmd/go/testdata/script: disable list_empty_importpath test on Windows

The test is flaking on windows, and I haven't been able to figure out
why. For now, to unblock folks, just allow the value that occasionally
appears: 'no errors' to avoid having a broken test. This seems like it's
probably a race though so we should fix it as soon as we can.

For #73976

Change-Id: I6a6a696431d784d048ed798b828a759e752b6393
Reviewed-on: https://go-review.googlesource.com/c/go/+/713220
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Matloob <matloob@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>

Author: matloob

src/cmd/go/testdata/script/list_empty_importpath.txt

@@ -1,6 +1,12 @@
 ! go list all
 ! stderr 'panic'
-stderr 'invalid import path'
+[!GOOS:windows] [!GOOS:solaris] stderr 'invalid import path'
+# #73976: Allow 'no errors' on Windows and Solaris until issue
+# is resolved to prevent flakes. 'no errors' is printed by
+# empty scanner.ErrorList errors so that's probably where the
+# message is coming from, though we don't know how.
+[GOOS:windows] stderr 'invalid import path|no errors'
+[GOOS:solaris] stderr 'invalid import path|no errors'
 
 # go list produces a package for 'p' but not for ''
 go list -e all