Bug 16682: Fix display if Batch patron modification tool does not get any patrons

To reproduce:
- Go to Tools->Batch patron modification
- Submit without filling any of  "Use a file", "Or use a patron list",
  "Or list card numbers..." or use a patron lists with zero members
Result: Screen without any information

To test:
- Apply patch
- Repeat steps above
- Verify that you get a nice message
- Verify that the tool works as before
  - with invalid card numbers only
  - with valid and invalid card numbers
  - with valid card numbers only

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit c0d420f42a)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>

koha-tmpl/intranet-tmpl/prog/en/modules/tools/modborrowers.tt

@@ -172,6 +172,12 @@
                 </form>
                 [% END %]
 
+                [% IF ( op == 'show') && (!borrowers) && (!notfoundcardnumbers) # Alert if no patrons given%]
+                    [% op = 'noshow' # Change op to prevent display in code below %]
+                    <h1>Batch patrons modification</h1>
+                    <div class="dialog alert">No patron card numbers given. <a href="/cgi-bin/koha/tools/modborrowers.pl" class="btn btn-mini">Back</a></div>
+                [% END #Alert if no patrons %]
+
                 [% IF ( op == 'show' or op == 'show_results' ) %]
                     [% IF ( op == 'show' ) %]
                         <h1>Batch patrons modification</h1>