Lilypond cannot resolve standard deutch.ly

[pihentagy]

After successfully installing lilypond:

curl -sSL https://git.io/getlyp | bash
lyp install lilypond

I got the following error:

$ lyp compile angelus.ly 
Lyp 1.3.1
Invalid include file specified in /home/pihentagy/gdrive/kotta/Ckotta/darabok/AngelusPastoribus/angelus-V1.ly:2: 

  \include "deutsch.ly"

/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:561:in `error'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:556:in `error'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:222:in `process_include_command'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:187:in `block (2 levels) in process_lilypond_file'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:184:in `scan'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:184:in `block in process_lilypond_file'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:182:in `each_line'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:182:in `process_lilypond_file'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:154:in `compile_dependency_tree'
/home/egerkon/.lyp/lib/app/lib/lyp/resolver.rb:80:in `resolve_package_dependencies'
/home/egerkon/.lyp/lib/app/lib/lyp/wrapper.rb:7:in `wrap'
/home/egerkon/.lyp/lib/app/lib/lyp/lilypond.rb:102:in `compile'
/home/egerkon/.lyp/lib/app/bin/lilypond:59:in `<main>'