Bug 37038: koha-elasticsearch creates a file named 0

Bug 37038: koha-elasticsearch creates a file named 0

After execution of koha-elasticsearch command a file named 0 remains in
the current directory.

Inside the single parentheses, the character '>' is treated as a file
redirection, not as a comparison operator.

Test plan:
==========
1. Have a test installation with Elasticsearch.  As root, perform:
   ./debian/scripts/koha-elasticsearch --rebuild kohadev
   When the command finishes, check the contents of the current
   directory (ls -ltr | tail).  You sould notice a fresh file named '0'
2. Apply the patch. Delete the file named 0.
3. Repeat p. 1.  There should be no file named 0 now.

Signed-off-by: Roman Dolny <roman.dolny@jezuici.pl>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>