dotnet: force ICU to be loaded during tests

pkgs/development/compilers/dotnet/common.nix

@@ -71,8 +71,10 @@
                 export DOTNET_ROOT=${runtime}
               '' + run);
 
+      # Setting LANG to something other than 'C' forces the runtime to search
+      # for ICU, which will be required in most user environments.
       checkConsoleOutput = command: ''
-        output="$(${command})"
+        output="$(LANG=C.UTF-8 ${command})"
         # yes, older SDKs omit the comma
         [[ "$output" =~ Hello,?\ World! ]] && touch "$out"
       '';