Hey,

running the following commands and trying to complete the last line
by pressing tab produces a zsh taking up 100% cpu. Strace says the zsh
is alternatingly running mmap and mremap with increasing sizes in a loop.

zsh -f
touch foo.bar
alias -s bar='echo a &'
foo.bar fo

zsh version:
zsh 5.2 (x86_64-debian-linux-gnu)

Best regards,
Michael