Volume split outputs file with ".001" extension when there's only one part

[dragonhunt02]

If a volume is created from a file baz smaller than selected volume size

mkdir temp
dd if=/dev/random of=baz bs=3M count=10
7zz a -tzip  -v1G temp/foo baz

7zip outputs one volume foo.zip.001.
This also happens if file is bigger than volume size, but compressed output size is smaller than volume size.

Expected behaviour is to output one file foo.zip.

File foo.zip.001 can be renamed to foo.zip and extracted with other software, so we can improve compatibility with this change.

[ip7z]

It can be expected that all created archive files will have file name extensions regardless of size.
For example, some script can copy created volumes with expected file name extensions (001, 002).

[dragonhunt02]

Indeed such change would require an appropriate flag to avoid breaking existing script pipelines