Fix packages flag

It should split on any whitespace

flags.go

@@ -117,15 +117,15 @@ func (c *commandValue) Value() []string {
 var _ pflag.Value = (*stringSlice)(nil)
 
 // stringSlice is a flag.Value which populates the string slice by splitting
-// the raw flag value on spaces.
+// the raw flag value on whitespace.
 type stringSlice []string
 
 func (s *stringSlice) String() string {
 	return strings.Join(*s, " ")
 }
 
 func (s *stringSlice) Set(raw string) error {
-	*s = append(*s, strings.Split(raw, " ")...)
+	*s = append(*s, strings.Fields(raw)...)
 	return nil
 }
 

flags_test.go

@@ -25,3 +25,11 @@ func TestNoSummaryValue_SetAndString(t *testing.T) {
 		assert.ErrorContains(t, value.Set("bogus"), "must be one or more of")
 	})
 }
+
+func TestStringSlice(t *testing.T) {
+	value := "one \ntwo  three\n\tfour\t five   \n"
+	var v []string
+	ss := (*stringSlice)(&v)
+	assert.NilError(t, ss.Set(value))
+	assert.DeepEqual(t, v, []string{"one", "two", "three", "four", "five"})
+}