Added STNODEFAULTFOLDER envvar to skip default folder creation on new

install.

cmd/syncthing/main.go

@@ -146,6 +146,10 @@ Development Settings
 The following environment variables modify syncthing's behavior in ways that
 are mostly useful for developers. Use with care.
 
+ STNODEFAULTFOLDER Don't create a default folder when starting for the first
+                   time.  This variable will be ignored anytime after the first
+                   run.
+
  STGUIASSETS       Directory to load GUI assets from. Overrides compiled in
                    assets.
 
@@ -188,6 +192,7 @@ The following are valid values for the STTRACE variable:
 var (
 	noUpgrade       = os.Getenv("STNOUPGRADE") != ""
 	innerProcess    = os.Getenv("STNORESTART") != "" || os.Getenv("STMONITORED") != ""
+	noDefaultFolder = os.Getenv("STNODEFAULTFOLDER") != ""
 )
 
 type RuntimeOptions struct {
@@ -990,18 +995,28 @@ func setupGUI(mainService *suture.Supervisor, cfg *config.Wrapper, m *model.Mode
 }
 
 func defaultConfig(myName string) config.Configuration {
-	defaultFolder := config.NewFolderConfiguration("default", locations[locDefFolder])
+	var defaultFolder config.FolderConfiguration
+
+	if !noDefaultFolder {
+		l.Infoln("Default folder created and/or linked to new config")
+
+		defaultFolder = config.NewFolderConfiguration("default", locations[locDefFolder])
 		defaultFolder.RescanIntervalS = 60
 		defaultFolder.MinDiskFreePct = 1
 		defaultFolder.Devices = []config.FolderDeviceConfiguration{{DeviceID: myID}}
 		defaultFolder.AutoNormalize = true
 		defaultFolder.MaxConflicts = -1
+	} else {
+		l.Infoln("We will skip creation of a default folder on first start since the proper envvar is set")
+	}
 
 	thisDevice := config.NewDeviceConfiguration(myID, myName)
 	thisDevice.Addresses = []string{"dynamic"}
 
 	newCfg := config.New(myID)
+	if !noDefaultFolder {
 		newCfg.Folders = []config.FolderConfiguration{defaultFolder}
+	}
 	newCfg.Devices = []config.DeviceConfiguration{thisDevice}
 
 	port, err := getFreePort("127.0.0.1", 8384)