Fixes to #947 broke ssh access to repositories

[trebonian]

• Gitea version (or commit ref): cf02cd7
• Git version: 2.13.0
• Operating system: Alpine Linux
• Database (use [x]):
  • PostgreSQL
  • [x ] MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • [x ] Not relevant
• Log gist: https://gist.github.com/trebonian/d9cbb2971eef6e4502e8e28fdb8bb4ca

Description

Any access to repository via git causes a crash. It appears that my repository wasn't migrated to include #947 team-units and the latest set of fixes try and access the units.
What procedure do I need to execute to update the repositories? Or can the code be more properly backwards compatible with the old repository version.

Screenshots

If this issue involves the Web Interface, please include a screenshot

[trebonian]

This appears to be the same as issue #1768 - sorry for duplicate.

alpine:~/gitea$ git remote show barry
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x80 pc=0x202f28bec0e]

goroutine 1 [running]:
panic(0x202f4215580, 0xc420010080)
/usr/lib/go/src/runtime/panic.go:500 +0x1a5
code.gitea.io/gitea/models.(*Repository).getUnitsByUserID(0xc4201a9340, 0x202f4b8bc80, 0xc420292280, 0x1, 0x1, 0x0, 0x0)
/srv/app/src/code.gitea.io/gitea/models/repo.go:361 +0x8e
code.gitea.io/gitea/models.(*Repository).CheckUnitUser(0xc4201a9340, 0x1, 0x1, 0x1, 0x0)
/srv/app/src/code.gitea.io/gitea/models/repo.go:334 +0x5c
code.gitea.io/gitea/cmd.runServ(0xc4200bf400, 0x0, 0xc4200bf400)
/srv/app/src/code.gitea.io/gitea/cmd/serv.go:253 +0x1e6d
code.gitea.io/gitea/vendor/github.com/urfave/cli.HandleAction(0x202f41cab00, 0x202f43b2a48, 0xc4200bf400, 0xc420053b00, 0x0)
/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/app.go:471 +0xbb
code.gitea.io/gitea/vendor/github.com/urfave/cli.Command.Run(0x202f38653bf, 0x4, 0x0, 0x0, 0x0, 0x0, 0x0, 0x202f38bd9bf, 0x2f, 0x0, ...)
/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/command.go:191 +0xcc9
code.gitea.io/gitea/vendor/github.com/urfave/cli.(*App).Run(0xc4203a2d00, 0xc42000c1c0, 0x4, 0x4, 0x0, 0x0)
/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/app.go:241 +0x6a5
main.main()
/srv/app/src/code.gitea.io/gitea/main.go:44 +0x3ac
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.