PNG clipart prevents export DVI / export PS

[Guenter Milde]

Dear LyX developers,

since the latest update/recompile of master:

  Version 2.4.0dev (Wednesday, 18 November 2020) 
  Built from git commit hash 0b9c2722
  Qt Version (run-time): 5.11.3
  Qt Version (compile-time): 5.11.3
  
export of lib/Intro.lyx (and other lib/*/Intro.lyx) document to DVI or PS
fails with 

  ! LaTeX Error: Cannot determine size of graphic in 4421914becf8ea0a5dc0bca7051d
  5117b9561dece5c4f1bd2ffc1c5c4c026dae_footnote_png.eps (no BoundingBox).

The offending graphics are clipart/footnote.png and 
clipart/reference.png.
I suppose a problem with the PNG -> EPS conversion.

* Does anyone else see the problem?

* I see no converter for this transformation (actually not for any PNG->*)
  in Tools>Preferences>Converters.
  
  Should this be handled by QT or am I missing an external converter
  dependency? 
 

The ctest failures for e.g. 

	1760 - export/doc/Intro_dvi (Failed)
	1761 - export/doc/Intro_dvi3_texF (Failed)
	1762 - export/doc/Intro_dvi3_systemF (Failed)
	1763 - export/doc/Intro_pdf (Failed)
	1765 - export/doc/Intro_pdf3 (Failed)

indicate that it normally should work.


Günter