Add support for setting old save path

config.go

@@ -23,4 +23,6 @@ type Config struct {
 	Draft bool
 	// Prerelease permits an upgrade to a "pre-release" version (default to false).
 	Prerelease bool
+	// To prevent automatic removal of the old binary, and allow you to test an update prior to manual removal.
+	OldSavePath string
 }

update.go

@@ -99,7 +99,8 @@ func (up *Updater) decompressAndUpdate(src io.Reader, assetName, assetURL, cmdPa
 
 	log.Printf("Will update %s to the latest downloaded from %s", cmdPath, assetURL)
 	return update.Apply(asset, update.Options{
-		TargetPath: cmdPath,
+		TargetPath:  cmdPath,
+		OldSavePath: up.oldSavePath,
 	})
 }
 

updater.go

@@ -19,6 +19,7 @@ type Updater struct {
 	universalArch string // only filled in when needed
 	prerelease    bool
 	draft         bool
+	oldSavePath   string
 }
 
 // keep the default updater instance in cache
@@ -71,6 +72,7 @@ func NewUpdater(config Config) (*Updater, error) {
 		universalArch: universalArch,
 		prerelease:    config.Prerelease,
 		draft:         config.Draft,
+		oldSavePath:   config.OldSavePath,
 	}, nil
 }