commit 21f18ab19f749d4a15096c3445121bc40e2dd55b
Author: Ben Rohlfs <brohlfs@google.com>
Date:   Tue Oct 13 23:03:08 2020 +0200

    Fix 'Send' button being enabled even without the user making any changes
    
    This could happen, if a label has a default vote that 'Send' would apply
    to the change. For the purpose of 'dirty checking' such default votes
    should not be considered.
    
    Change-Id: I6108c8723e1eba853fe0c4241bac0f733b4e3a89

diff --git a/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores.ts b/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores.ts
index 245c65f..2e9189e 100644
--- a/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores.ts
+++ b/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores.ts
@@ -61,7 +61,7 @@ export class GrLabelScores extends GestureEventListeners(
   @property({type: Object})
   _labelValues?: LabelValuesMap;
 
-  getLabelValues(): LabelNameToValuesMap {
+  getLabelValues(includeDefaults = true): LabelNameToValuesMap {
     const labels: LabelNameToValuesMap = {};
     if (this.shadowRoot === null || !this.change) {
       return labels;
@@ -106,8 +106,12 @@ export class GrLabelScores extends GestureEventListeners(
         prevValNum = prevVal;
       }
 
+      const defValNum = this._getDefaultValue(this.change.labels, label);
+
       if (selectedVal !== prevValNum) {
-        labels[label] = selectedVal;
+        if (includeDefaults || !!prevValNum || selectedVal !== defValNum) {
+          labels[label] = selectedVal;
+        }
       }
     }
     return labels;
@@ -126,6 +130,12 @@ export class GrLabelScores extends GestureEventListeners(
     return numberValue;
   }
 
+  _getDefaultValue(labels?: LabelNameToInfoMap, labelName?: string) {
+    if (!labelName || !labels?.[labelName]) return undefined;
+    const labelInfo = labels[labelName] as DetailedLabelInfo;
+    return labelInfo.default_value;
+  }
+
   _getVoteForAccount(
     labels: LabelNameToInfoMap | undefined,
     labelName: string,
diff --git a/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores_test.js b/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores_test.js
index ffc17cd..ae639e1 100644
--- a/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores_test.js
+++ b/polygerrit-ui/app/elements/change/gr-label-scores/gr-label-scores_test.js
@@ -99,6 +99,22 @@ suite('gr-label-scores tests', () => {
     });
   });
 
+  test('getLabelValues includeDefaults', async () => {
+    element.change = {
+      _number: '123',
+      labels: {
+        'Code-Review': {
+          values: {'0': 'meh', '+1': 'good', '-1': 'bad'},
+          default_value: 0,
+        },
+      },
+    };
+    await flush();
+
+    assert.deepEqual(element.getLabelValues(true), {'Code-Review': 0});
+    assert.deepEqual(element.getLabelValues(false), {});
+  });
+
   test('_getVoteForAccount', () => {
     const labelName = 'Code-Review';
     assert.strictEqual(element._getVoteForAccount(
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
index 50bf411..1afaa64 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
@@ -321,6 +321,11 @@ export class GrReplyDialog extends KeyboardShortcutMixin(
   @property({type: Boolean})
   _reviewersMutated = false;
 
+  /**
+   * Signifies that the user has changed their vote on a label or (if they have
+   * not yet voted on a label) if a selected vote is different from the default
+   * vote.
+   */
   @property({type: Boolean})
   _labelsChanged = false;
 
@@ -1368,7 +1373,7 @@ export class GrReplyDialog extends KeyboardShortcutMixin(
 
   _handleLabelsChanged() {
     this._labelsChanged =
-      Object.keys(this.$.labelScores.getLabelValues()).length !== 0;
+      Object.keys(this.$.labelScores.getLabelValues(false)).length !== 0;
   }
 
   _isState(knownLatestState?: LatestPatchState, value?: LatestPatchState) {