TestInvalidFileFormat fails on windows because of /

This issue has mutated since it was first seen. An effort was made to fix this fail, but it is not complete.

Fixed in model-acls. This test failure also currently affects master FWIW:

PS C:\Users\Administrator\golang\src\github.com\juju\juju> go test ./cmd/juju/service --gocheck.f=Invalid

----------------------------------------------------------------------
FAIL: deploy_test.go:124: DeploySuite.TestInvalidFileFormat

[snip]

deploy_test.go:130:
    c.Assert(err, gc.ErrorMatches,
        `invalid charm or bundle provided at ".*`+filepath.FromSlash("/bundle.yaml")+`"`)
... error string = "invalid charm or bundle provided at \"C:\\\\Users\\\\ADMINI~1\\\\AppData\\\\Local\\\\Temp\\\\2\\\\ch
eck-7327674107095723743\\\\7\\\\bundle.yaml\""
... regex string = "invalid charm or bundle provided at \".*\\bundle.yaml\""

[snip]

OOPS: 13 passed, 1 FAILED
--- FAIL: TestPackage (16.17 seconds)
FAIL
FAIL github.com/juju/juju/cmd/juju/service 18.618s
PS C:\Users\Administrator\golang\src\github.com\juju\juju> git log -1 --pretty=format:%H
45cc6aa81dc491d292b0e5731652017409e71f1c
PS C:\Users\Administrator\golang\src\github.com\juju\juju>

I have an approved fix for it, https://github.com/juju/juju/pull/4756, but I can't land it because master is currently blocked.