It is probably due to bundled icu within webkitgtk4.

Actually as tpopela pointed out this happen not only on s390 but on all supported arches.

So we were thinking about possible solutions.

1. Add a conflict between webkitgtk4-debuginfo and icu-debuginfo, but that would not help that much as calling debuginfo-install webkitgtk4 would end with error as some packages will require icu-debuginfo (to satisfy i.e. glib2 debuginfo requirements) as well as webkitgtk4-debuginfo in one transaction - conflict. Basically this won't change anything.

2. Remove icu files from webkitgtk4-debuginfo. On paper the easiest solution, but I didn't found a way how to do so. Compiling the bundled icu with -g0 still includes the icu files in webkitgtk4-debuginfo package. I thought that they are some macros for filtering the included files (like for requires/provides filtering), but it looks like there is none.

3. Call this bug a "feature" until this is solved on the rpm/rpmbuild level. As I think that webkitgtk4 is not the only package that is bundling some library (more specifically the same library that is provided by the system, but newer version).  

I will change the component to rpm, as from the webkitgtk4 maintainer POV, there is nothing I can't do right now.

OK, so here is a really ugly way how to achieve solution number 2.

diff --git a/webkitgtk4.spec b/webkitgtk4.spec
index 96aec16..235a9f0 100644
--- a/webkitgtk4.spec
+++ b/webkitgtk4.spec
@@ -212,6 +212,19 @@ Requires:       %{name} = %{version}-%{release}
 %description    plugin-process-gtk2
 Support for the GTK+ 2 based NPAPI plugins (such as Adobe Flash) for %{name}.

+%define debug_package %{nil}
+%global __debug_package 1
+
+%package debuginfo
+Summary: Debug information for package %{name}
+
+%description debuginfo
+This package provides debug information for package %{name}.
+Debug information is useful when developing applications that use this
+package or when debugging this package.
+
+%files debuginfo -f debugfiles.list
+
 %prep
 %if 0%{?bundle_icu}
 %setup -q -T -n icu -b 1
@@ -383,6 +396,10 @@ popd
 %add_to_license_files Source/WTF/wtf/dtoa/COPYING
 %add_to_license_files Source/WTF/wtf/dtoa/LICENSE

+%check
+sed -i '\!/usr/src/debug/icu!d' debugfiles.list
+rm -rf %{buildroot}/usr/src/debug/icu
+
 %post -p /sbin/ldconfig
 %postun -p /sbin/ldconfig
 %post jsc -p /sbin/ldconfig

But I really don't like it, nor I don't know if it's not causing some other problems, but the webkitgtk4-debuginfo does not contain the icu files anymore.

There is another solution that is actually used by valgrind mentioned at
https://lists.fedoraproject.org/archives/list/devel%40lists.fedoraproject.org/message/RQEIXS6WDORE2AAAWHPUD6WGQVMCY6KW/

In the end I implemented the solution mentioned in the comment 6.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0703