unoconv aborts if output file is in /tmp and named "out.xlsx"

This is hard to believe, so I'm reluctant to submit this. But here it is:

If the effective output file path specified -o <path> is a certain filename, then unoconv aborts with an exception, but no abort occurs if a different file name or directory is used (and yes, I checked that the file did not already exist). For me, outputting to "out.xlsx" when in /tmp aborted but not if using any other output filename; however when in some other directory (/home/myuser/ptmp/J), output to "xout.xlsx" started aborting but using "out.xlsx" worked without error.

So there is some kind of state which remembers past file names (or something) and causes havoc.

I tried temporarily removing $HOME/.config/libreoffice* but that did not help (also tried setting the UserInstallation environment variable).

The exception is:

document.storeToURL(outputurl, tuple(outputprops) )
uno.IOException: SfxBaseModel::impl_store <file:///tmp/out.xlsx> failed: 0x11b(Error Area:Io Class:Abort Code:27)

$ ls -ld /tmp
drwxrwxrwt 31 root root 980 Feb 10 18:46 /tmp/

$ mount | grep /tmp
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime,size=52428800k)

$ df -h /tmp
Filesystem Size Used Avail Use% Mounted on
tmpfs 50G 572K 50G 1% /tmp

$ unoconv --version
unoconv 0.7
platform posix/linux
python 3.8.5 (default, Jul 28 2020, 12:59:40)
[GCC 9.3.0]
LibreOffice 6.4.6.2

I tried a new, clean user-config directory, thinking there might be something corrupted in mine; but it makes no difference (export UserInstallation... in the script below)

*** STEPS TO REPRODUCE ***

1. cd /tmp
2. echo "foo,bar" >demo.csv
3. unoconv -d spreadsheet -f xlsx -o out.xlsx demo.csv
   (or try xout.xlsx, alternating between tries)

RESULTS:

Traceback (most recent call last):
  File "/usr/bin/unoconv", line 1037, in convert
    document.storeToURL(outputurl, tuple(outputprops) )
uno.IOException: SfxBaseModel::impl_store <file:///tmp/out.xlsx> failed: 0x11b(Error Area:Io Class:Abort Code:27)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/unoconv", line 1282, in <module>
    main()
  File "/usr/bin/unoconv", line 1198, in main
    convertor.convert(inputfn)
  File "/usr/bin/unoconv", line 1039, in convert
    raise UnoException("Unable to store document to %s (ErrCode %d)\n\nProperties: %s" % (outputurl, e.ErrCode, outputprops), None)
  File "/usr/lib/python3/dist-packages/uno.py", line 516, in _uno_struct__getattr__
    return getattr(self.__dict__["value"], name)
AttributeError: ErrCode

NOTE: Change "out.xlsx" to "xout.xlsx" and no error occurs!

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: unoconv 0.7-2
ProcVersionSignature: Ubuntu 5.4.0-65.73-generic 5.4.78
Uname: Linux 5.4.0-65-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Feb 10 18:39:17 2021
InstallationDate: Installed on 2020-03-24 (323 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
PackageArchitecture: all
SourcePackage: unoconv
UpgradeStatus: Upgraded to focal on 2020-05-16 (270 days ago)