This fixes a bug upstream by temporarily using a patched version of go-i18n.
Closes #7838
        github.com/ghodss/yaml v1.0.0
        github.com/gobuffalo/flect v0.2.2
        github.com/gobwas/glob v0.2.3
+       github.com/gohugoio/go-i18n v2.1.3-0.20210430103248-4c28c89f8013+incompatible // indirect
+       github.com/gohugoio/go-i18n/v2 v2.1.3-0.20210430103248-4c28c89f8013
        github.com/gohugoio/testmodBuilder/mods v0.0.0-20190520184928-c56af20f2e95
        github.com/google/go-cmp v0.5.5
        github.com/gorilla/websocket v1.4.2
        github.com/mitchellh/mapstructure v1.3.3
        github.com/muesli/smartcrop v0.3.0
        github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 // indirect
-       github.com/nicksnyder/go-i18n/v2 v2.1.2
        github.com/niklasfasching/go-org v1.5.0
        github.com/olekukonko/tablewriter v0.0.5
        github.com/pelletier/go-toml v1.9.0
 
 github.com/gobwas/glob v0.2.3/go.mod h1:d3Ez4x06l9bZtSvzIay5+Yzi0fmZzPgnTbPcKjJAkT8=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
+github.com/gohugoio/go-i18n v2.1.3-0.20210430103248-4c28c89f8013+incompatible h1:0d/CxRl9eRy8UOO86f80axTI2TcP1hEEgExnhFKXIkw=
+github.com/gohugoio/go-i18n v2.1.3-0.20210430103248-4c28c89f8013+incompatible/go.mod h1:KyP0P5LEhJdtIq9PYxFiaxeWtFngJO5zLkDvEiqG8gI=
+github.com/gohugoio/go-i18n/v2 v2.1.3-0.20210430103248-4c28c89f8013 h1:Nj29Qbkt0bZ/bJl8eccfxQp3NlU/0IW1v9eyYtQ53XQ=
+github.com/gohugoio/go-i18n/v2 v2.1.3-0.20210430103248-4c28c89f8013/go.mod h1:3Ltoo9Banwq0gOtcOwxuHG6omk+AwsQPADyw2vQYOJQ=
 github.com/gohugoio/testmodBuilder/mods v0.0.0-20190520184928-c56af20f2e95 h1:sgew0XCnZwnzpWxTt3V8LLiCO7OQi3C6dycaE67wfkU=
 github.com/gohugoio/testmodBuilder/mods v0.0.0-20190520184928-c56af20f2e95/go.mod h1:bOlVlCa1/RajcHpXkrUXPSHB/Re1UnlXxD1Qp8SKOd8=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 
        "github.com/gohugoio/hugo/config"
        "github.com/gohugoio/hugo/helpers"
 
-       "github.com/nicksnyder/go-i18n/v2/i18n"
+       "github.com/gohugoio/go-i18n/v2/i18n"
 )
 
 type translateFunc func(translationID string, templateData interface{}) string
 
                expected:     "3 minuttar lesing",
                expectedFlag: "3 minuttar lesing",
        },
+       // Issue #7838
+       {
+               name: "unknown-language-codes",
+               data: map[string][]byte{
+                       "en.toml": []byte(`[readingTime]
+one ="en one"
+other = "en count {{.Count}}"`),
+                       "a1.toml": []byte(`[readingTime]
+one =  "a1 one"
+other = "a1 count {{ .Count }}"`),
+                       "a2.toml": []byte(`[readingTime]
+one =  "a2 one"
+other = "a2 count {{ .Count }}"`),
+               },
+               args:         3,
+               lang:         "a2",
+               id:           "readingTime",
+               expected:     "a2 count 3",
+               expectedFlag: "a2 count 3",
+       },
        // https://github.com/gohugoio/hugo/issues/7798
        {
                name: "known-language-missing-plural",
 
        yaml "gopkg.in/yaml.v2"
 
        "github.com/gohugoio/hugo/helpers"
-       "github.com/nicksnyder/go-i18n/v2/i18n"
+       "github.com/gohugoio/go-i18n/v2/i18n"
        toml "github.com/pelletier/go-toml"
 
        "github.com/gohugoio/hugo/deps"