I am also seeing this problem with Juju 1.20.1-trusty-amd64 on local provider.
mbruzek@workhorse:~/workspace/charms/precise/nfs$ juju set nfs storage_root= panic: runtime error: index out of range
goroutine 1 [running]: runtime.panic(0xcc1300, 0x19ec9b7) /usr/lib/go/src/pkg/runtime/panic.c:266 +0xb6 main.(*SetCommand).Run(0xc210142180, 0xc2100e0000, 0x0, 0x0) /build/buildd/juju-core-1.20.1/src/github.com/juju/juju/cmd/juju/set.go:92 +0x62d github.com/juju/juju/cmd/envcmd.(*environCommandWrapper).Run(0xc210141c80, 0xc2100e0000, 0xb27740, 0xc210151410) /build/buildd/juju-core-1.20.1/src/github.com/juju/juju/cmd/envcmd/environmentcommand.go:1 +0x3d main.(*envCmdWrapper).Run(0xc210141ca0, 0xc2100e0000, 0x0, 0x0) /build/buildd/juju-core-1.20.1/src/github.com/juju/juju/cmd/juju/addmachine.go:1 +0x3d github.com/juju/cmd.(*SuperCommand).Run(0xc210121580, 0xc2100e0000, 0xc2100e0000, 0x0) /build/buildd/juju-core-1.20.1/src/github.com/juju/cmd/supercommand.go:321 +0x3ca github.com/juju/cmd.Main(0x7f84c73a11f0, 0xc210121580, 0xc2100e0000, 0xc21000a010, 0x3, ...) /build/buildd/juju-core-1.20.1/src/github.com/juju/cmd/cmd.go:247 +0x283 main.Main(0xc21000a000, 0x4, 0x4) /build/buildd/juju-core-1.20.1/src/github.com/juju/juju/cmd/juju/main.go:77 +0xada main.main() /build/buildd/juju-core-1.20.1/src/github.com/juju/juju/cmd/juju/main.go:174 +0x44
goroutine 3 [syscall]: os/signal.loop() /usr/lib/go/src/pkg/os/signal/signal_unix.go:21 +0x1e created by os/signal.init·1 /usr/lib/go/src/pkg/os/signal/signal_unix.go:27 +0x31
goroutine 12 [syscall]: runtime.goexit() /usr/lib/go/src/pkg/runtime/proc.c:1394
I am also seeing this problem with Juju 1.20.1-trusty-amd64 on local provider.
mbruzek@ workhorse: ~/workspace/ charms/ precise/ nfs$ juju set nfs storage_root=
panic: runtime error: index out of range
goroutine 1 [running]: panic(0xcc1300, 0x19ec9b7)
/usr/lib/ go/src/ pkg/runtime/ panic.c: 266 +0xb6 SetCommand) .Run(0xc2101421 80, 0xc2100e0000, 0x0, 0x0)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ juju/cmd/ juju/set. go:92 +0x62d com/juju/ juju/cmd/ envcmd. (*environComman dWrapper) .Run(0xc210141c 80, 0xc2100e0000, 0xb27740, 0xc210151410)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ juju/cmd/ envcmd/ environmentcomm and.go: 1 +0x3d envCmdWrapper) .Run(0xc210141c a0, 0xc2100e0000, 0x0, 0x0)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ juju/cmd/ juju/addmachine .go:1 +0x3d com/juju/ cmd.(*SuperComm and).Run( 0xc210121580, 0xc2100e0000, 0xc2100e0000, 0x0)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ cmd/supercomman d.go:321 +0x3ca com/juju/ cmd.Main( 0x7f84c73a11f0, 0xc210121580, 0xc2100e0000, 0xc21000a010, 0x3, ...)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ cmd/cmd. go:247 +0x283 0xc21000a000, 0x4, 0x4)
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ juju/cmd/ juju/main. go:77 +0xada
/build/ buildd/ juju-core- 1.20.1/ src/github. com/juju/ juju/cmd/ juju/main. go:174 +0x44
runtime.
main.(*
github.
main.(*
github.
github.
main.Main(
main.main()
goroutine 3 [syscall]:
/usr/lib/ go/src/ pkg/os/ signal/ signal_ unix.go: 21 +0x1e
/usr/lib/ go/src/ pkg/os/ signal/ signal_ unix.go: 27 +0x31
os/signal.loop()
created by os/signal.init·1
goroutine 12 [syscall]:
/usr/lib/ go/src/ pkg/runtime/ proc.c: 1394
runtime.goexit()