gnucash maint: Warn if can't lock for any reason other than that the file is locked already.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/a3871d9c (commit)
	from  https://github.com/Gnucash/gnucash/commit/9ed0174c (commit)



commit a3871d9ca1b12fa1635d1ac7f3781c4a490030ef
Author: John Ralls <jralls at ceridwen.us>
Date:   Sun Jun 23 11:01:29 2019 -0700

    Warn if can't lock for any reason other than that the file is locked already.
    
    And include the error string in the message.



Summary of changes:
 libgnucash/backend/xml/gnc-xml-backend.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)