Cygwin: Asciidoctor hangs on asciidoctor-diagram use

[RandomCore]

I just stumbled across the issue #254 and may (still) have the same problem under Cygwin (versions below):

$ ls -a
.  ..  example.adoc
$ cat example.adoc
= Some title

A diagram with plan-uml:

[.text-center]
[subs="attributes"]
[plantuml,"structure",png]
....
@startsalt
{
   { T
    + <&folder> /
    ++ <&folder> usr
    +++ <&folder> share
   }
}
....

End.
$ asciidoctor -r asciidoctor-diagram -o example.html example.adoc

This hangs for ever and no output (example.html or .asciidoctor/structure.png) is generated.

I use Windows 10 (Professional Ver 10.0 Build 18363) and a recent cygwin (v3.12). Some more version info:

$ ruby --version
ruby 2.6.4p104 (2019-08-28 revision 67798) [x86_64-cygwin]
$ bundle
Using Ascii85 1.0.3
Using public_suffix 4.0.3
Using addressable 2.7.0
Using afm 0.2.2
Using asciidoctor 2.0.10
Using asciidoctor-diagram 2.0.1
Using concurrent-ruby 1.1.5
Using pdf-core 0.7.0
Using ttfunk 1.5.1
Using prawn 2.2.2
Using prawn-icon 2.5.0
Using css_parser 1.7.1
Using prawn-svg 0.30.0
Using prawn-table 0.2.2
Using hashery 2.1.2
Using ruby-rc4 0.1.5
Using pdf-reader 2.4.0
Using prawn-templates 0.1.2
Using safe_yaml 1.0.5
Using thread_safe 0.3.6
Using polyglot 0.3.5
Using treetop 1.5.3
Using asciidoctor-pdf 1.5.0.rc.2
Using bundler 1.17.2
Using rouge 3.15.0

Any ideas?

[RandomCore]

Version v1.5.3 fixes the problem. Thanks.