fix comment and add some logging in discovery

plugin/discovery/find.go

@@ -2,6 +2,7 @@ package discovery
 
 import (
 	"io/ioutil"
+	"log"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -55,6 +56,8 @@ func findPluginPaths(kind string, machineName string, dirs []string) []string {
 			continue
 		}
 
+		log.Printf("[DEBUG] checking for plugins in %q", baseDir)
+
 		for _, item := range baseItems {
 			fullName := item.Name()
 
@@ -66,6 +69,8 @@ func findPluginPaths(kind string, machineName string, dirs []string) []string {
 					continue
 				}
 
+				log.Printf("[DEBUG] checking for plugins in %q", machineDir)
+
 				for _, item := range machineItems {
 					fullName := item.Name()
 
@@ -83,6 +88,8 @@ func findPluginPaths(kind string, machineName string, dirs []string) []string {
 						continue
 					}
 
+					log.Printf("[DEBUG] found plugin %q", fullName)
+
 					ret = append(ret, filepath.Clean(absPath))
 				}
 
@@ -96,6 +103,8 @@ func findPluginPaths(kind string, machineName string, dirs []string) []string {
 					continue
 				}
 
+				log.Printf("[DEBUG] found legacy plugin %q", fullName)
+
 				ret = append(ret, filepath.Clean(absPath))
 			}
 		}

plugin/discovery/meta_set.go

@@ -115,7 +115,7 @@ func (s PluginMetaSet) Newest() PluginMeta {
 // name and an appropriate version.
 //
 // If any of the given requirements match *no* plugins then its PluginMetaSet
-// in the returned map will be nil.
+// in the returned map will be empty.
 //
 // All viable metas are returned, so the caller can apply any desired filtering
 // to reduce down to a single option. For example, calling Newest() to obtain