Redis session broken after upgrade to 1.3.0

[dh-harald]

• Gitea version (or commit ref): 1.3.0 (docker image)
• Git version: 2.13.5
• Operating system: alpine-linux
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:

Description

After upgrading the docker image to 1.3.0, I can't use redis session...
The application drops this exception:

panic: session/redis: unsupported option '/app/gitea/network'

goroutine 1 [running]:
code.gitea.io/gitea/vendor/github.com/go-macaron/session.Sessioner(0xc420972900, 0x1, 0x1, 0x5619a67efc40, 0xc42086e540)
	/srv/app/src/code.gitea.io/gitea/vendor/github.com/go-macaron/session/session.go:149 +0x285
code.gitea.io/gitea/routers/routes.NewMacaron(0xc42028da40)
	/srv/app/src/code.gitea.io/gitea/routers/routes/routes.go:109 +0x996
code.gitea.io/gitea/cmd.runWeb(0xc42028da40, 0x0, 0x0)
	/srv/app/src/code.gitea.io/gitea/cmd/web.go:65 +0xc1
code.gitea.io/gitea/vendor/github.com/urfave/cli.HandleAction(0x5619a67ef820, 0x5619a695f368, 0xc42028da40, 0xc42012f800, 0x0)
	/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/app.go:471 +0xb9
code.gitea.io/gitea/vendor/github.com/urfave/cli.Command.Run(0x5619a6132b0f, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x5619a6156d46, 0x16, 0x0, ...)
	/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/command.go:191 +0xa74
code.gitea.io/gitea/vendor/github.com/urfave/cli.(*App).Run(0xc4201b1ba0, 0xc42000c060, 0x2, 0x2, 0x0, 0x0)
	/srv/app/src/code.gitea.io/gitea/vendor/github.com/urfave/cli/app.go:241 +0x601
main.main()
	/srv/app/src/code.gitea.io/gitea/main.go:48 +0x3a7

I'm using the usual config in session:

[session]
PROVIDER        = redis
PROVIDER_CONFIG = network=tcp,addr=redis:6379,db=0,pool_size=100,idle_timeout=180

After a short investigation I've found this commit:
8798cf4#diff-60f5fca6d29eafbb30eb645a0cd4041fR1347
I think, this could be a problem, because it's excepting file (instead of redis configuration) and joins it with AppWorkPath