I used `gh pr checkout https://github.com/myorg/myrepo/pull/90`, and got
this:
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xf0a477]
goroutine 1 [running]:
github.com/cli/cli/v2/pkg/cmd/pr/checkout.checkoutRun(0xc000696380)
github.com/cli/cli/v2/pkg/cmd/pr/checkout/checkout.go:136 +0x777
github.com/cli/cli/v2/pkg/cmd/pr/checkout.NewCmdCheckout.func1(0xc000819808?, {0xc0006ef460, 0x1, 0x12e9718?})
github.com/cli/cli/v2/pkg/cmd/pr/checkout/checkout.go:61 +0x274
github.com/spf13/cobra.(*Command).execute(0xc000819808, {0xc0006ef440, 0x1, 0x1})
github.com/spf13/cobra/command.go:1015 +0xaaa
github.com/spf13/cobra.(*Command).ExecuteC(0xc0004b2f08)
github.com/spf13/cobra/command.go:1148 +0x46f
github.com/spf13/cobra.(*Command).ExecuteContextC(...)
github.com/spf13/cobra/command.go:1080
main.mainRun()
github.com/cli/cli/v2/cmd/gh/main.go:119 +0x53b
main.main()
github.com/cli/cli/v2/cmd/gh/main.go:46 +0x13
Repeating it gave the same issue.
Dropping the URL and just doing `gh pr checkout 90` worked.