Description:
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I was trying to process Apache logfiles with PHP. The default LogFormat timestamp
%t translates to '[d/M/Y:H:i:s O]' in date() notation.
PHP fails to create DateTime instances if the format argument contains timezone
placeholders like O P e

I am aware of the 3rd parameter of DateTime::createFromFormat() to pass timezone
information. 
- the documentation says 'Format accepted by date()'
- DateTime is supposed to help parsing datetime formats, not to restrict

Test script:
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$dt = DateTime::createFromFormat('[d/M/Y:H:i:s O]', '[13/Mar/1969:23:40:00 +0100]');
print($dt->format('c'));

Expected result:
----------------
1969-03-13T23:40:00+01:00

Actual result:
--------------
Fatal error: Call to a member function format() on a non-object