Ensure reasons end up as comments in kubectl edit.

pkg/kubectl/cmd/util/editor/BUILD

@@ -41,7 +41,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["editor_test.go"],
+    srcs = [
+        "editoptions_test.go",
+        "editor_test.go",
+    ],
     embed = [":go_default_library"],
 )
 

pkg/kubectl/cmd/util/editor/editoptions.go

@@ -657,12 +657,12 @@ func (h *editHeader) writeTo(w io.Writer, editMode EditMode) error {
 
 	for _, r := range h.reasons {
 		if len(r.other) > 0 {
-			fmt.Fprintf(w, "# %s:\n", r.head)
+			fmt.Fprintf(w, "# %s:\n", hashOnLineBreak(r.head))
 		} else {
-			fmt.Fprintf(w, "# %s\n", r.head)
+			fmt.Fprintf(w, "# %s\n", hashOnLineBreak(r.head))
 		}
 		for _, o := range r.other {
-			fmt.Fprintf(w, "# * %s\n", o)
+			fmt.Fprintf(w, "# * %s\n", hashOnLineBreak(o))
 		}
 		fmt.Fprintln(w, "#")
 	}
@@ -738,3 +738,18 @@ func hasLines(r io.Reader) (bool, error) {
 	}
 	return false, nil
 }
+
+// hashOnLineBreak returns a string built from the provided string by inserting any necessary '#'
+// characters after '\n' characters, indicating a comment.
+func hashOnLineBreak(s string) string {
+	r := ""
+	for i, ch := range s {
+		j := i + 1
+		if j < len(s) && ch == '\n' && s[j] != '#' {
+			r += "\n# "
+		} else {
+			r += string(ch)
+		}
+	}
+	return r
+}

pkg/kubectl/cmd/util/editor/editoptions_test.go

+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package editor
+
+import (
+	"testing"
+)
+
+func TestHashOnLineBreak(t *testing.T) {
+	tests := []struct {
+		original string
+		expected string
+	}{
+		{
+			original: "",
+			expected: "",
+		},
+		{
+			original: "\n",
+			expected: "\n",
+		},
+		{
+			original: "a\na\na\n",
+			expected: "a\n# a\n# a\n",
+		},
+		{
+			original: "a\n\n\na\n\n",
+			expected: "a\n# \n# \n# a\n# \n",
+		},
+	}
+	for _, test := range tests {
+		r := hashOnLineBreak(test.original)
+		if r != test.expected {
+			t.Errorf("expected: %s, saw: %s", test.expected, r)
+		}
+	}
+}