Fix hugo server "Watching for changes" path display

especially when the given `--source` path is a relative directory.

Also, when `--source` is specified, make WorkingDir an absolute path
from the very beginning, to be consistent with the case when `--source`
is not given.  Otherwise, the function name helpers.AbsPathify(), which
prepends WorkingDir to a relative path, does not really make sense.

Fixes #1721

commands/server.go

@@ -159,7 +159,7 @@ func server(cmd *cobra.Command, args []string) error {
 	// Watch runs its own server as part of the routine
 	if serverWatch {
 		watchDirs := getDirList()
-		baseWatchDir := helpers.AbsPathify(viper.GetString("WorkingDir"))
+		baseWatchDir := viper.GetString("WorkingDir")
 		for i, dir := range watchDirs {
 			watchDirs[i], _ = helpers.GetRelativePath(dir, baseWatchDir)
 		}