title: Android constraint layout strange behavior
body: <p>The version of my  constraint layout is <code>1.0.0-alpha8</code> . After I have included a toolbar in my layout , there is space in both left and right side of the toolbar, like the image below</p>
  
  <p><a href="https://i.stack.imgur.com/gY9ka.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gY9ka.png" alt="enter image description here"></a></p>
  
  <p>Here is the code for my toolbar </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.v7.widget.Toolbar
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      android:layout_width="match_parent"
      android:layout_height="?attr/actionBarSize"
      android:background="@color/colorPrimary"&gt;
  
  
  &lt;/android.support.v7.widget.Toolbar&gt;
  </code></pre>
  
  <p>Which I have included in my layout in following way </p>
  
  <pre><code>&lt;include
      layout="@layout/toolbar_top"
      android:id="@+id/topPanel"
      android:layout_height="wrap_content"
      android:layout_width="match_parent"/&gt;
  </code></pre>
  
  <p>I didn't used any additional padding or margin in my root element of the layout file . </p>
  
  <p>Another stange thing is if I compile or build the program my code automatically changed, like </p>
  
  <pre><code>&lt;include
      layout="@layout/toolbar_top"
      android:id="@+id/topPanel"
      android:layout_height="wrap_content"
      android:layout_width="match_parent"/&gt;
  </code></pre>
  
  <p>Change to </p>
  
  <pre><code>&lt;include
      layout="@layout/toolbar_top"
      android:id="@+id/topPanel"
      android:layout_height="wrap_content"
      android:layout_width="368dp"/&gt;
  </code></pre>
  
  <p>And the guideline also add some additional value which I didn't write, like <code>layout_editor_absoluteX</code> automatically added .</p>
  
  <pre><code>&lt;android.support.constraint.Guideline
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/guideline1"
      android:orientation="vertical"
      app:layout_constraintGuide_percent="0.15"
      tools:layout_editor_absoluteX="58dp"/&gt;
  </code></pre>