Use forked urfave/cli until upstream patch is merged

current master version of urfave/cli has a bug where values set by the
environment var are not saved to the stringslice var.

Once urfave/cli#1178 is merged, we can switch
back to using the upstream version.

go.mod

@@ -57,6 +57,7 @@ require (
 	github.com/smartystreets/goconvey v0.0.0-20190330032615-68dc04aab96a // indirect
 	github.com/spf13/cobra v0.0.3 // indirect
 	github.com/stretchr/testify v1.5.1
+	github.com/urfave/cli v1.22.2
 	github.com/urfave/cli/v2 v2.1.1
 	github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
@@ -82,3 +83,5 @@ replace (
 	github.com/jaguilar/vt100 => github.com/tonistiigi/vt100 v0.0.0-20190402012908-ad4c4a574305
 	github.com/moby/buildkit => github.com/earthly/buildkit v0.7.1-0.20200818031448-40e935c0a18c
 )
+
+replace github.com/urfave/cli/v2 => github.com/alexcb/cli/v2 v2.2.1-0.20200824212017-2ae03fa69ce7

go.sum

@@ -9,6 +9,8 @@ github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03
 github.com/Microsoft/go-winio v0.4.15-0.20190919025122-fc70bd9a86b5/go.mod h1:tTuCMEN+UleMWgg9dVx4Hu52b1bJo+59jBh3ajtinzw=
 github.com/Microsoft/hcsshim v0.8.9/go.mod h1:5692vkUqntj1idxauYlpoINNKeqCiG6Sg38RRsjT5y8=
 github.com/Shopify/logrus-bugsnag v0.0.0-20171204204709-577dee27f20d/go.mod h1:HI8ITrYtUY+O+ZhtlqUnD8+KwNPOyugEhfP9fdUIaEQ=
+github.com/alexcb/cli/v2 v2.2.1-0.20200824212017-2ae03fa69ce7 h1:s+/0XkLpoNCal1XGTNFwR39Day1E3po1rpyEePjehSA=
+github.com/alexcb/cli/v2 v2.2.1-0.20200824212017-2ae03fa69ce7/go.mod h1:SE9GqnLQmjVa0iPEY0f1w3ygNIYcIJ0OKPMoW2caLfQ=
 github.com/antlr/antlr4 v0.0.0-20200225173536-225249fdaef5 h1:nkZ9axP+MvUFCu8JRN/MCY+DmTfs6lY7hE0QnJbxSdI=
 github.com/antlr/antlr4 v0.0.0-20200225173536-225249fdaef5/go.mod h1:T7PbCXFs94rrTttyxjbyT5+/1V8T2TYDejxUfHJjw1Y=
 github.com/apache/thrift v0.0.0-20161221203622-b2a4d4ae21c7/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb+bacwQ=
@@ -251,6 +253,7 @@ github.com/urfave/cli v0.0.0-20171014202726-7bc6a0acffa5/go.mod h1:70zkFmudgCuE/
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/urfave/cli v1.22.2 h1:gsqYFH8bb9ekPA12kRo0hfjngWQjkJPlN9R0N78BoUo=
 github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
+github.com/urfave/cli v1.22.4 h1:u7tSpNPPswAFymm8IehJhy4uJMlUuU/GmqSkvJ1InXA=
 github.com/urfave/cli/v2 v2.1.1 h1:Qt8FeAtxE/vfdrLmR3rxR6JRE0RoVmbXu8+6kZtYU4k=
 github.com/urfave/cli/v2 v2.1.1/go.mod h1:SE9GqnLQmjVa0iPEY0f1w3ygNIYcIJ0OKPMoW2caLfQ=
 github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE=