Seadrive CLI doesn't sync files with .tmp extension

I just notice this phenomenon today when I am creating a file with *.tmp as the extension, which is not uploaded to the Seafile server. After changing it to other extension, it will be synced. Is it by design or bug? because I didn’t notice it’s mentioned anywhere.
I am using the Seadrive CLI under Ubuntu. Not sure if it applies to Seadrive’s other platforms or not.

Some temporary files are ignored by design.

Maybe better to make ignore list configurable? With keeping *.tmp files ignored by default.