title: Replace function not working as expected with Dask
body: <p>I'm reading a dask dataframe:</p>
  <pre><code>ddf = dd.read_csv({...}, dtype='object')
  </code></pre>
  <p>Next, I'm trying to replace commas with dots, so values can injected in a SQL DB as floats.</p>
  <pre><code>ddf = ddf.replace(&quot;,&quot;, &quot;.&quot;)
  </code></pre>
  <p>However, when I'm call <code>ddf.to_sql({...})</code> my code is returning <code>ValueError: Unable to parse string &quot;2,0&quot; at position 8</code>, which suggests that the replace function is not working as expected. Why is this the case? Is there another way to replace commas with dots in Dask?</p>