Use third party library without namespace in TYPO3 Flow

I'd like to use parsedown class (http://parsedown.org/) within a TYPO3 Flow Project (latest TYPO3 Flow version). I installed parsedown via

composer require erusev/parsedown dev-master

The class is loaded by the autoloader, but it can't be used without getting an error in /Data/Temporary/Development/Cache/Code/Flow_Object_Classes/Parsedown.php on line 1092. The incorrect line in the temp file is:

namespace ;

If this line is uncommented, everything works like expected.

I couldn't find help in the manual (see http://docs.typo3.org/flow/TYPO3FlowDocumentation/stable/TheDefinitiveGuide/PartIII/PackageManagement.html#using-3rd-party-packages). I'm just at the very beginning using TYPO3 Flow, so any help is highly appreciated (before I create a pointless bug report at TYPO3).

This is a known bug, see Bug #52944, Generating correct proxy classes for classes without a namespace.

There is also a (not yet merged) patch for the problem