Aggregate library projects install issue.

[Blady-Com]

Hello,
Given an aggregate library project gnoga_agg.gpr of gnoga.gpr library project.
See attached test case test29.zip.
Gnoga withs the library project lib_components.gpr.
When I compile the aggregate library all is well:

$ gprbuild -p -P gnoga_agg.gpr 
Setup
   [mkdir]        object directory for project Lib_Components
   [mkdir]        library directory for project Lib_Components
   [mkdir]        object directory for project Gnoga
   [mkdir]        library directory for project Gnoga
   [mkdir]        library directory for project Gnoga_Agg
Compile
   [Ada]          xpm.adb
   [Ada]          gnoga.adb
Build Libraries
   [gprlib]       components.lexch
   [archive]      libcomponents.a
   [index]        libcomponents.a
   [gprlib]       gnoga_agg.lexch
   [archive]      libgnoga_agg.a
   [index]        libgnoga_agg.a

When I install lib_components.gpr project all is well (apart warnings):

$ gprinstall -p -f --prefix="inst" sc/lib_components.gpr 
Install project Lib_Components
warning: file does not exist '/users/blady/documents/programmation/gnat/tests/test29/sc/parser-examples/*'
warning: file does not exist '/users/blady/documents/programmation/gnat/tests/test29/sc/obj/components//gnatdoc/*'

When I install gnoga_agg.gpr aggregate library project all seems well:

$ gprinstall -p -f --prefix="inst" gnoga_agg.gpr 
Install project Gnoga_Agg

But the install project doesn't with lib_components.gpr:

--  This project has been generated by GPRINSTALL Community 2018 (20180523) (x86_64-apple-darwin16.7.0)

library project Gnoga_Agg is
   type BUILD_KIND is ("default");
   BUILD : BUILD_KIND := external("GNOGA_AGG_BUILD", "default");

as it should:

--  This project has been generated by GPRINSTALL Community 2018 (20180523) (x86_64-apple-darwin16.7.0)

with "lib_components";

library project Gnoga is
   type BUILD_KIND is ("default");

How to get the library lib_components withed?

Thanks, Pascal.