Created attachment 151094 [details]
The spreadsheet "nobug.ods" which is used at the start of the bug report description
This is a truly bizarre bug that I've spent a lot of time diagnosing and reducing to a simple case. This description is quite long. Please bear with me.
You need an unusual folder on an NFS share. Here, we have a group called "silson". My username is "nigel". The folder has the group sticky bit set, so that files are created with group silson and everybody in that group shares write access. Here is the set-up for folder "test". I don't think the acls are relevant, but included just in case.
[root@hermes Silson Library]# ls -ld test
drwxrwsr-x+ 2 nigel silson 4096 Apr 30 15:29 test
[root@hermes Silson Library]# getfacl test
# file: test
# owner: nigel
# group: silson
Now, open the attached file and save it into this folder with libreoffice calc, as "nobug"
Now, insert a chart. Select A1:B8. Insert|Chart. X-Y scatter, Points & Lines, Finish. Save as "bug"
Click on the chart and press backspace to delete it. Save as "fixedbug"
The file protections are:
ls test/* -l
-rw-rw-r--+ 1 nigel nigel 14994 Apr 30 15:37 test/bug.ods
-rw-rw-r--+ 1 nigel silson 9050 Apr 30 15:38 test/fixedbug.ods
-rw-rw-r--+ 1 nigel silson 9056 Apr 30 15:34 test/nobug.ods
It's the presence of a chart that makes the file get saved with group=nigel instead of group=silson. It can be a chart hidden away on a different work-sheet that nobody ever looks at ....
The bug was not present in the libreoffice shipped with Fedora 27: 126.96.36.199-3.fc27.x86_64. It appeared after upgrading to Fedora 29, 188.8.131.52-5.fc29.x86_64
Created attachment 151095 [details]
The file "bug.ods", in case you want to look at its internals
Just confirmed that this bug is also present in 184.108.40.206 as downloaded from https://www.libreoffice.org/download/download/