gnucash maint: [commodity-utils] partially revert eac79bd506395120

[Christopher Lam]

Updated	 via  https://github.com/Gnucash/gnucash/commit/48c3c8bc (commit)
	from  https://github.com/Gnucash/gnucash/commit/810d283e (commit)



commit 48c3c8bc511f181f5de90ea079ec20d5c6dd2a0e
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Tue May 7 20:34:55 2019 +0800

    [commodity-utils] partially revert eac79bd506395120
    
    The eac79bd506395120 commit was slightly overzealous - if pair was #f,
    originally this make-exchange-function would create a function that
    returns (gnc:make-gnc-monetary domestic 0); I thought it was
    acceptable to return #f instead but this would lead to report
    crash. Revert previous behaviour.



Summary of changes:
 gnucash/report/report-system/commodity-utilities.scm | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)