bug#35625: Python3 Cannot Find Existing Shared Library within guix environment

[Jesse Gibbons <jgibbons2357@gmail.com>]

I brought this to the help mailing list, and now I see it as a
particular bug in guix. When I change into a guix environment and try
to run a Python project that uses the WebKitGTK2 library, it cannot
find the specified shared library, even though it is in $LIBRARY_PATH.
As a result, the project crashes. This does not happen when I call guix
build. On a side note, guix build fails due to another error (possibly
related).

Thanks in advance for looking into this.
-Jesse


Package Definition:
#!
see https://github.com/jendrikseipp/rednotebook
!#
(define-module (custom packages rednotebook)
  #:use-module (guix packages)
  #:use-module (guix download)
  #:use-module (guix build-system python)
  #:use-module (guix licenses))
(define-public rednotebook

  (package
   (name "rednotebook")
   (version "2.11.1")
   (source
    (origin
     (method url-fetch)
     (uri (string-append
	   "https://github.com/jendrikseipp/rednotebook/archive/v"
	   version
	   ".tar.gz"))
     (sha256
      (base32
       "15n1ziypfj3lzpvhha7r637zrb259l9yrcsvkic9cg5mndiaivs3"))))
   (build-system python-build-system)
   (inputs
    `(("python" ,(@ (gnu packages python) python-3))))
   (propagated-inputs
    `(("python-pygobject"
       ,(@ (gnu packages glib) python-pygobject))
      ("gtk+" ,(@ (gnu packages gtk) gtk+))
      ("gtksourceview"
       ,(@ (gnu packages gtk) gtksourceview-3))
      ("webkitgtk"
       ,(@ (gnu packages webkit) webkitgtk-2.24))
      ("python-pyyaml"
       ,(@ (gnu packages python-xyz) python-pyyaml))))
   (home-page "https://www.rednotebook.app")
   (synopsis #f)
   (description
    "RedNotebook is a modern desktop journal. It lets you format, tag and search your entries. You can also add pictures, links and customizable templates, spell check your notes, and export to plain text, HTML, Latex or PDF.")
   (license gpl2+))
  )


Program log (streams merged):
Adding /home/jesse/Documents/rednotebook/rednotebook-2.11.1 to sys.path
2019-05-07 16:15:41,122 INFO     Writing log to file "/home/jesse/.rednotebook/rednotebook.log"
2019-05-07 16:15:41,122 INFO     System encoding: utf-8
2019-05-07 16:15:41,122 INFO     Language code: None
rednotebook/journal.py:161: PyGIDeprecationWarning: Since version 3.11, calling threads_init is no longer needed. See: https://wiki.gnome.org/PyGObject/Threading
  GObject.threads_init()
2019-05-07 16:15:41,182 WARNING  For spell checking, please install enchant (python3-enchant).

** (journal.py:2179): WARNING **: 16:15:41.209: Failed to load shared library 'libwebkit2gtk-4.0.so.37' referenced by the typelib: libwebkit2gtk-4.0.so.37: cannot open shared object file: No such file or directory

** (journal.py:2179): WARNING **: 16:15:41.209: Failed to load shared library 'libjavascriptcoregtk-4.0.so.18' referenced by the typelib: libjavascriptcoregtk-4.0.so.18: cannot open shared object file: No such file or directory
/gnu/store/kz1d84nv5rlqdf415i16wz8zvf492l1c-profile/lib/python3.7/site-packages/gi/types.py:226: Warning: cannot derive 'rednotebook+gui+browser+Browser' from non-derivable parent type 'void'
  _gi.type_register(cls, namespace.get('__gtype_name__'))
Traceback (most recent call last):
  File "rednotebook/journal.py", line 168, in <module>
    from rednotebook.gui.main_window import MainWindow
  File "/home/jesse/Documents/rednotebook/rednotebook-2.11.1/rednotebook/gui/main_window.py", line 45, in <module>
    from rednotebook.gui import browser
  File "/home/jesse/Documents/rednotebook/rednotebook-2.11.1/rednotebook/gui/browser.py", line 41, in <module>
    class Browser(WebKit2.WebView):
  File "/gnu/store/kz1d84nv5rlqdf415i16wz8zvf492l1c-profile/lib/python3.7/site-packages/gi/types.py", line 235, in __init__
    super(GObjectMeta, cls).__init__(name, bases, dict_)
  File "/gnu/store/kz1d84nv5rlqdf415i16wz8zvf492l1c-profile/lib/python3.7/site-packages/gi/types.py", line 214, in __init__
    cls._type_register(cls.__dict__)
  File "/gnu/store/kz1d84nv5rlqdf415i16wz8zvf492l1c-profile/lib/python3.7/site-packages/gi/types.py", line 226, in _type_register
    _gi.type_register(cls, namespace.get('__gtype_name__'))
RuntimeError: could not create new GType: rednotebook+gui+browser+Browser (subclass of void)