Skip grep tests which fail intermittently on s390x

The grep tests succeed and fail intermittently on s390x.  Until that
arch is more established and works (or fails) consistently, skip these
tests rather than let s390x hold back ever other arch.

git.spec

@@ -633,6 +633,10 @@ grep -E  "$not_core_re" bin-man-doc-files \
     | grep -v "credential-gnome-keyring" > bin-man-doc-git-files
 
 %check
+%ifarch s390x
+# Skip grep tests which fail intermittently on s390x
+export GIT_SKIP_TESTS="t7810"
+%endif
 make test
 
 %clean
@@ -785,6 +789,7 @@ rm -rf %{buildroot}
 %changelog
 * Sun Jun 25 2017 Todd Zullinger <tmz@pobox.com> - 2.13.2-1
 - Update to 2.13.2
+- Skip grep tests which fail intermittently on s390x
 
 * Wed Jun 07 2017 Jitka Plesnikova <jplesnik@redhat.com> - 2.13.1-2
 - Perl 5.26 re-rebuild of bootstrapped packages