`pytest` CI step fails due to go panic from `tests-plugin-cli`

## Meta:

**CircleCI CLI Version:**

```
circleci@4ced5db8e415:~$ circleci version
Build Agent version: 1.0.287269-f2b94789
Built: 2025-07-31T16:47:08+0000
```

**CircleCI Tests Plugin CLI Version:**

```
Installing circleci-tests-plugin-cli plugin.
circleci-tests-plugin-cli plugin Installed. Version: 1.0.9952-dcfc394
```

**Operating System:**

```
circleci@4ced5db8e415:~$ uname -a
Linux 4ced5db8e415 6.8.0-1031-aws #33~22.04.1-Ubuntu SMP Thu Jun 26 14:22:30 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
```

**CircleCI CLI Diagnostic:**

```
circleci@4ced5db8e415:~$ sudo circleci diagnostic

---
CircleCI CLI Diagnostics
---
Debugger mode: false
Config found: /root/.circleci/cli.yml
API host: https://circleci.com
API endpoint: graphql-unstable
OK, got a token.
Hello, Violet Folino Gallo.
```

---

## Current behavior:

The failure occurs during a step which runs a pytest suite as shown below.
```
Pytest command passed to circleci test run:
xargs python -m pytest --junitxml=/tmp/test-results/pytest/results-0.xml -vv --capture=tee-sys --disable-warnings --durations=50 --durations-min=0.1 --conn=pipeliner/sql/tests/conn/postgres.conn --conn=pipeliner/sql/tests/conn/sqlite.conn --conn=pipeliner/sql/tests/conn/presto.conn --conn=pipeliner/sql/tests/conn/sql_server.conn --conn=pipeliner/sql/tests/conn/mysql.conn --conn=/tmp/bigquery.conn --conn=/tmp/snowflake.conn --conn=/tmp/databricks.conn --conn=/tmp/redshift_circleci.conn --maxfail=50 -o junit_family=xunit1 -o junit_logging=all --tb=short
```
Eventually the tests all complete and pass, so the job _should_ return a successful result.
```
= 711 passed, 19 skipped, 60 xfailed, 4 xpassed, 667 warnings in 135.80s (0:02:15) =
DEBU[2025-07-30T22:11:06Z] Completed tests
DEBU[2025-07-30T22:11:06Z] ending execution
```
Instead, a go panic occurs immediately afterwards and the step exits with a failure code.
```
panic: cant have gotCon after getCon

goroutine 1 [running]:
github.com/circleci/backplane-go/httpcl.(*request).gotCon(0xc000136150, {{0xd9b758?, 0xc000274e08?}, 0x80?, 0xf8?, 0x1345160?})
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/metrics.go:320 +0x1250
net/http.http2traceGotConn(0xc00003c3c0?, 0xc000103340, 0x0)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/h2_bundle.go:10916 +0x203
net/http.(*http2Transport).RoundTripOpt(0xc000122280, 0xc000124500, {0xc0?, 0xc3?})
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/h2_bundle.go:8062 +0x1d7
net/http.(*http2Transport).RoundTrip(...)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/h2_bundle.go:8014
net/http.http2noDialH2RoundTripper.RoundTrip({0xc000132000?}, 0xc000124500?)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/h2_bundle.go:10872 +0x1c
net/http.(*Transport).roundTrip(0xc000132000, 0xc0001243c0)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/transport.go:615 +0x497
net/http.(*Transport).RoundTrip(0x470fd9?, 0x148?)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/roundtrip.go:30 +0x13
github.com/circleci/backplane-go/httpcl.(*Metrics).RoundTrip(0xc000136000, 0xc0001243c0)
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/metrics.go:71 +0x74
net/http.send(0xc0001243c0, {0xd90500, 0xc000136000}, {0xc000282801?, 0xc000138048?, 0x0?})
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/client.go:259 +0x5e2
net/http.(*Client).send(0xc0001202a0, 0xc0001243c0, {0x407d8e?, 0xc000466cc0?, 0x0?})
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/client.go:180 +0x91
net/http.(*Client).do(0xc0001202a0, 0xc0001243c0)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/client.go:728 +0x989
net/http.(*Client).Do(...)
/home/circleci/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.5.linux-amd64/src/net/http/client.go:587
github.com/circleci/backplane-go/httpcl.(*Client).retryRequest.func1(0xc0001c2de0)
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/httpclient.go:632 +0x752
github.com/circleci/backplane-go/httpcl.Retry({0xd96210, 0x1345160}, 0xc00071a060)
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/retry.go:62 +0x16f
github.com/circleci/backplane-go/httpcl.(*Client).retryRequest(0xc000126270, {0xd96210, 0x1345160}, {0xc0000108c0, 0xb}, {{0xc65c86, 0x4}, {0xc6b8b7, 0x6}, {0xc1ade0, ...}, ...}, ...)
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/httpclient.go:689 +0x29c
github.com/circleci/backplane-go/httpcl.(*Client).Call(0xc000126270, {0xd96210, 0x1345160}, {{0xc65c86, 0x4}, {0xc6b8b7, 0x6}, {0xc1ade0, 0xc0001be000}, {0x0, ...}, ...})
/home/circleci/go/pkg/mod/github.com/circleci/backplane-go@v0.43.18887/httpcl/httpclient.go:552 +0x4fe
github.com/circleci/tests-plugin-cli/internal/events.(*EventPublisher).sendEvent(0xc0001202d0, {0xd96210, 0x1345160}, {0xc753d5, 0xe}, {0xc6ee0b, 0x7}, 0xc0001888a0, {0xb97ca0, 0xc0001885d0})
/home/circleci/project/internal/events/publisher.go:93 +0x2aa
github.com/circleci/tests-plugin-cli/internal/events.SendEvent({0xd96210?, 0x1345160?}, 0x419705?, {0xc753d5?, 0x0?}, {0xc6ee0b?, 0xc000249ec0?}, 0xa6a38c?, {0xb97ca0, 0xc0001885d0})
/home/circleci/project/internal/events/publisher.go:108 +0x72
github.com/circleci/tests-plugin-cli/cmd.(*TestPluginCommand).Execute(0xc000077e60)
/home/circleci/project/cmd/root.go:71 +0x2a5
github.com/circleci/tests-plugin-cli/cmd.Execute()
/home/circleci/project/cmd/root.go:108 +0x65
main.main()
/home/circleci/project/main.go:14 +0xbb
Error: exit status 2

Exited with code exit status 1
```

## Expected behavior:

When the command passed to circleci succeeds, the CI step should succeed.

## When did this begin / Was this previously working?:

The failure is intermittent, but was first observed on 29 July and has happened multiple times since then.

## Additional Information:

Happy to answer any follow up questions for me.

Start by reading internal/events/publisher.go around EventPublisher.sendEvent and cmd/root.go around TestPluginCommand.Execute, then reproduce the reported pytest run through the tests plugin. Done means a successful test command does not trigger the Go panic and the CI step exits successfully.

Written by the indexing model from the issue text.