Repository: go
Issue: x/build: `gomote ssh` to plan9-arm fails with `Failed to get IP out of "pi4g": <nil>`
Labels: OS-Plan9,Builders,NeedsFix,arch-arm


<details><summary><code>~/go/src$ go1.19beta1 version -m $(which gomote)</code></summary>

<pre>
/usr/local/google/home/bcmills/bin/gomote: devel go1.19-b9c4d94fdb Fri Jun 24 18:54:27 2022 +0000
	path	golang.org/x/build/cmd/gomote
	mod	golang.org/x/build	v0.0.0-20220623213349-3ceb9f4e34a9	h1:UXzH6j5xqqdwolS/8sIboizJIjD1FchifnbxqrO4wro=
	dep	cloud.google.com/go/compute	v1.3.0	h1:mPL/MzDDYHsh5tHRS9mhmhWlcgClCrCa6ApQCU6wnHI=
	dep	github.com/aws/aws-sdk-go	v1.30.15	h1:Sd8QDVzzE8Sl+xNccmdj0HwMrFowv6uVUx9tGsCE1ZE=
	dep	github.com/golang/groupcache	v0.0.0-20200121045136-8c9f03a8e57e	h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
	dep	github.com/golang/protobuf	v1.5.2	h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
	dep	github.com/googleapis/gax-go/v2	v2.1.1	h1:dp3bWCh+PPO1zjRRiCSczJav13sBvG4UhNyVTa1KqdU=
	dep	github.com/jmespath/go-jmespath	v0.4.0	h1:BEgLn5cpjn8UN1mAw4NjwDrS35OdebyEtFe+9YPoQUg=
	dep	go.opencensus.io	v0.23.0	h1:gqCw0LfLxScz8irSi8exQc7fyQ0fKQU/qnC/X8+V/1M=
	dep	golang.org/x/net	v0.0.0-20220127200216-cd36cc0744dd	h1:O7DYs+zxREGLKzKoMQrtrEacpb0ZVXA5rIwylE2Xchk=
	dep	golang.org/x/oauth2	v0.0.0-20211104180415-d3ed0bb246c8	h1:RerP+noqYHUQ8CMRcPlC2nvTa4dcBIjegkuWdcUDuqg=
	dep	golang.org/x/sync	v0.0.0-20210220032951-036812b2e83c	h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
	dep	golang.org/x/sys	v0.0.0-20220209214540-3681064d5158	h1:rm+CHSpPEEW2IsXUib1ThaHIjuBVZjxNgSKmBLFfD4c=
	dep	golang.org/x/text	v0.3.7	h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
	dep	golang.org/x/time	v0.0.0-20210723032227-1f47c861a9ac	h1:7zkz7BUtwNFFqcowJ+RIgu2MaV/MapERkDIy+mwPyjs=
	dep	google.golang.org/api	v0.70.0	h1:67zQnAE0T2rB0A3CwLSas0K+SbVzSxP+zTLkQLexeiw=
	dep	google.golang.org/genproto	v0.0.0-20220222213610-43724f9ea8cf	h1:SVYXkUz2yZS9FWb2Gm8ivSlbNQzL2Z/NpPKE3RG2jWk=
	dep	google.golang.org/grpc	v1.44.0	h1:weqSxi/TMs1SqFRMHCtBgXRs8k3X39QIDEZ0pRcttUg=
	dep	google.golang.org/protobuf	v1.27.1	h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
	dep	gopkg.in/inf.v0	v0.9.1	h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=
	build	-compiler=gc
	build	CGO_ENABLED=1
	build	CGO_CFLAGS=
	build	CGO_CPPFLAGS=
	build	CGO_CXXFLAGS=
	build	CGO_LDFLAGS=
	build	GOARCH=amd64
	build	GOOS=linux
	build	GOAMD64=v1
</pre>

</details>

### What did you do?

```
~/go/src$ gomote create plan9-arm
# host type "host-plan9-arm-0intro" is not elastic; 2 of 1 machines connected, 2 busy
# canceled a post-submit build on a machine of type "host-plan9-arm-0intro"; it should reconnect and get assigned to you
…
~/go/src$ gomote ssh --i-will-not-break-the-host user-bcmills-plan9-arm-0
```

### What did you expect to see?

A successful SSH connection to a builder for the `plan9/arm` platform.

### What did you see instead?

```
$ ssh -p 2222 mutable-user-bcmills-plan9-arm-0@farmer.golang.org # auth using https://github.com/bcmills.keys
Enter passphrase for key '/usr/local/google/home/bcmills/.ssh/id_rsa':
# Welcome to the gomote ssh proxy, bcmills.
# Connecting to/starting remote ssh...
#
# `gomote push` and the builders use:
# - workdir: /boot/workdir
# - GOROOT: /boot/workdir/go
# - GOPATH: /boot/workdir/gopath
# - env: GO_BUILDER_NAME=plan9-arm
# Happy debugging.
# Plan9 user/pass: glenda/glenda123
# Failed to get IP out of "pi4g": <nil>
Connection to farmer.golang.org closed.
```

(attn @golang/plan9; CC @golang/release)