This is something that has been bugging me for a while and I always stumble on it trying to remember which form to use
I can't find anything in the changelog that looks similar to this having been fixed 

Downloading:
vague@IS-C0HVFBY:~$ /usr/bin/scp root@amodev:"/root/projects/management-packs/XI\ Gridhost.json" .
root@amodev's password:
XI Gridhost.json
vague@IS-C0HVFBY:~$ /usr/bin/scp root@amodev:"/root/projects/management-packs/XI Gridhost.json" .                                                                                                                                                                                                                             
root@amodev's password:                                                                                                                                                                                                                                                                                                       
scp: /root/projects/management-packs/XI: No such file or directory                                                                                                                                                                                                                                                            
scp: Gridhost.json: No such file or directory  
vague@IS-C0HVFBY:~$ /usr/bin/scp "root@amodev:/root/projects/management-packs/XI\ Gridhost.json" .                                                                                                                                                                                                                            
root@amodev's password:                                                                                                                                                                                                                                                                                                       
XI Gridhost.json
vague@IS-C0HVFBY:~$ /usr/bin/scp root@amodev:/root/projects/management-packs/XI\ Gridhost.json .                                                                                                                                                                                                                              
root@amodev's password:                                                                                                                                                                                                                                                                                                       
scp: /root/projects/management-packs/XI: No such file or directory                                                                                                                                                                                                                                                            
scp: Gridhost.json: No such file or directory

Uploading:
vague@IS-C0HVFBY:~$ /usr/bin/scp "XI\ Gridhost.json" admin@remote:                                                                                                                                                                                                                                                           
admin@remote's password:                                                                                                                                                                                                                                                                                                    
XI\ Gridhost.json: No such file or directory     
vague@IS-C0HVFBY:~$ /usr/bin/scp "XI Gridhost.json" admin@remote:                                                                                                                                                                                                                                                            
admin@remote's password:                                                                                                                                                                                                                                                                                                    
XI Gridhost.json                                                                                                                                                                                                                                                                             
vague@IS-C0HVFBY:~$ /usr/bin/scp XI\ Gridhost.json admin@remote:                                                                                                                                                                                                                                                            
admin@remote's password:                                                                                                                                                                                                                                                                                                    
XI Gridhost.json