Add warning when source version control system is not git

Author: twpayne

cmd/config.go

@@ -37,6 +37,7 @@ type sourceVCSConfig struct {
 	AutoCommit bool
 	AutoPush   bool
 	Init       interface{}
+	NotGit     bool
 	Pull       interface{}
 }
 

cmd/root.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/coreos/go-semver/semver"
@@ -93,6 +94,13 @@ func init() {
 					"warning: to disable this warning, set gpg.recipient in your config file instead\n",
 				)
 			}
+			if config.SourceVCS.Command != "" && !config.SourceVCS.NotGit && !strings.Contains(filepath.Base(config.SourceVCS.Command), "git") {
+				rootCmd.Printf("" +
+					"warning: it looks like you are using a version control system that is not git which will be deprecated in v2\n" +
+					"warning: please report this at https://github.com/twpayne/chezmoi/issues/459\n" +
+					"warning: to disable this warning, set sourceVCS.notGit = true in your config file\n",
+				)
+			}
 		case os.IsNotExist(err):
 		default:
 			printErrorAndExit(err)