[cipd] Remove dead expandTemplate function

cipd/client/cipd/client.go

Index: cipd/client/cipd/client.go
diff --git a/cipd/client/cipd/client.go b/cipd/client/cipd/client.go
index 2e0fea965ec02a6a6189963d3ff571dcb962d79c..b0b0f5bfa1c5e7207af0ef74fa5dd2c334464940 100644
--- a/cipd/client/cipd/client.go
+++ b/cipd/client/cipd/client.go
@@ -40,9 +40,7 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
-	"regexp"
 	"sort"
-	"strings"
 	"sync"
 	"time"
 
@@ -1403,58 +1401,3 @@ func buildInstanceIDMap(pins []common.Pin) map[string]string {
 	}
 	return out
 }
-
-var templateParm = regexp.MustCompile(`\${[^}]*}`)
-var errSkipTemplate = errors.New("this template should be skipped")
-
-// expandTemplate applies template expansion rules to the package template,
-// using the provided platform and arch values. If err == errSkipTemplate, that
-// means that this template does not apply to this platform/arch combination and
-// should be skipped.
-func expandTemplate(template, platform, arch string) (pkg string, err error) {
-	skip := false
-
-	expansionLookup := map[string]string{
-		"platform": platform,
-		"arch":     arch,
-	}
-
-	pkg = templateParm.ReplaceAllStringFunc(template, func(parm string) string {
-		// ${...}
-		contents := parm[2 : len(parm)-1]
-
-		varNameValues := strings.SplitN(contents, "=", 2)
-		if len(varNameValues) == 1 {
-			// ${varName}
-			if value, ok := expansionLookup[varNameValues[0]]; ok {
-				return value
-			}
-
-			err = errors.Reason("unknown variable in ${%(contents)s}").
-				D("contents", contents).Err()
-		}
-
-		// ${varName=value,value}
-		ourValue, ok := expansionLookup[varNameValues[0]]
-		if !ok {
-			err = errors.Reason("unknown variable in %(parm)s").D("parm", parm).Err()
-			return parm
-		}
-
-		for _, val := range strings.Split(varNameValues[1], ",") {
-			if val == ourValue {
-				return ourValue
-			}
-		}
-		skip = true
-		return parm
-	})
-	if skip {
-		err = errSkipTemplate
-	}
-	if err == nil && strings.ContainsRune(pkg, '$') {
-		err = errors.Reason("unable to process some variables in %(template)q").
-			D("template", template).Err()
-	}
-	return
-}