title: pyspark: read partitioned parquet "my_file.parquet/col1=NOW" string value replaced by <current_time> on read()
body: <p>With pyspark 3.1.1 on wsl Debian 10</p>
  <p>When reading parquet file partitioned with a column containing the string <code>NOW</code>, the string is replaced by the current time at the moment of the <code>read()</code> funct is executed. I suppose that <code>NOW</code> string interpreted as <code>now()</code></p>
  <pre><code># step to reproduce
  df = spark.createDataFrame(data=[(&quot;NOW&quot;,1), (&quot;TEST&quot;, 2)], schema = [&quot;col1&quot;, &quot;id&quot;])
  df.write.partitionBy(&quot;col1&quot;).parquet(&quot;test/test.parquet&quot;)
  &gt;&gt;&gt; /home/test/test.parquet/col1=NOW
  
  df_loaded = spark.read.option(
   &quot;basePath&quot;,
   &quot;test/test.parquet&quot;,
  ).parquet(&quot;test/test.parquet/col1=*&quot;)
  df_loaded.show(truncate=False)
  &gt;&gt;&gt; 
  +---+--------------------------+
  |id |col1                      |
  +---+--------------------------+
  |2  |TEST                      |
  |1  |2021-04-18 14:36:46.532273|
  +---+--------------------------+
  </code></pre>
  <p>Is that a bug or a normal function of pyspark?
  if the latter, is there a <code>sparkContext</code> option to avoid that behaviour?</p>