title: loadOptions getting called for same string which was searched earlier and cacheOptions is enabled
body: <p>I am trying to use <code>AsyncSelect</code> from <code>react-select</code> library.</p>
  <p>I have enabled <code>cacheOptions</code> option.</p>
  <p>Using below mentioned steps I am seeing an issue with <code>loadOptions</code></p>
  <ol>
  <li>Search for a string <code>test</code></li>
  <li>List of options gets displayed</li>
  <li><code>Clear</code> the input field</li>
  <li>Enter <code>same string</code> again <code>test</code></li>
  <li>Immediately displays <code>same list of options</code></li>
  <li><code>loadOptions</code> fires an API with search input <code>tes</code></li>
  <li><code>Clear</code> the input field</li>
  <li>Enter <code>same string</code> again <code>test</code></li>
  <li>Immediately displays <code>same list of options</code></li>
  <li>loadOptions fires API with search input <code>te</code>.</li>
  </ol>
  <p>I am not sure why loadOptions getting fired in this scenario if I am entering the same search string.</p>
  <p>Here is the <code>AsyncSelect</code></p>
  <pre><code>&lt;AsyncSelect
    classNamePrefix=&quot;select-item&quot;
    onChange={ onOptionSelect }
    getOptionValue={ item =&gt; item.id }
    placeholder=&quot;Search by Item&quot;
    formatOptionLabel={ company =&gt; &lt;CompanyWithIcon Item={ Item } /&gt; }
    loadOptions={ loadOptions }
    styles={ customStyles }
    isSearchable
    cacheOptions
    isClearable
  /&gt;
  </code></pre>
  <p>Here is the <code>loadOptions</code> function</p>
  <pre><code>const loadOptions = inputValue =&gt; searchItem(inputValue);
  </code></pre>
  <p>Can anybody please help?</p>