Bug 14422: Typo in updatedatabase.pl

Bug 14422: Typo in updatedatabase.pl

TEST PLAN
---------
 1) backup db
 2) git checkout -b my_3.6.x origin/3.6.x
 3) drop db and create blank one
 4) git reset --hard origin/3.6.x
 5) run web installer
 6) set HomeorHoldingBranchReturn system preference to 'holdingbranch'.
 7) create a Default checkout, hold rule
    home -> koha administration -> Circulation and fines rules
    -- I put 10 checkouts total and clicked 'Save'
    -- there currently is not 'returnbranch' in default_circ_rules.
 8) git reset --hard origin/3.20.x
    -- or whatever version you apply this to
       (3.8.x, 3.10.x, 3.14.x, 3.16.x, 3.18.x, or 3.20.x
        -- 3.21.00.008 deletes the systempreference involved)
 9) ./installer/data/mysql/updatedatabase.pl
10) check HomeorHoldingBranchReturn systempreference
    -- Currently says 'holdingbranch', but
       the value of 'returnbranch' in default_circ_rules is
       'homebranch'.
11) repeat steps 3-8
12) apply this patch
13) repeat steps 9-10
    -- Currently says 'holdingbranch', and
       the value of 'returnbranch' in default_circ_rules is
       'holdingbranch'.
14) run koha qa test tools

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Tested using 3.6.x install, updated to 3.8.x
Value is preserved
No errors

Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Note: I haven't followed the test plan, but the fix is trivial.
Maybe it could worth to upate 3.21.00.008 and check the value of
HomeOrHoldingBranchReturn before deleting it.
We could raise a warning if HomeOrHoldingBranchReturn ==
'holdingbranch'.
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>