xsel issue

gistfile1.md

$ zsh --version
zsh 5.0.7 (x86_64-unknown-linux-gnu)
$ xsel --version
xsel version 1.2.0 by Conrad Parker <conrad@vergenet.net>

$ history -nm 'find *' 1 | wc -l
107
$ history -nm 'find *' 1 | xsel -ib; xsel -ob | wc -l
0

$ history -nm 'find *' 1 | head -n 99 | wc -l        
99
$ history -nm 'find *' 1 | head -n 99 | xsel -ib; xsel -ob | wc -l
99

$ history -nm 'find *' 1 | head -n 100 | wc -l                    
100
$ history -nm 'find *' 1 | head -n 100 | xsel -ib; xsel -ob | wc -l
0