[lmi] Is this a zsh anomaly?

[Greg Chicares]

This (cygwin) bash session behaves as I expect:

$ cat Makefile

all:

        echo $(MAKEFLAGS)


$ export coefficiency='--jobs=4 --output-sync=recurse'


$ make -j3

echo  -j --jobserver-fds=3,4

-j --jobserver-fds=3,4


But this zsh session behaves differently:

$export coefficiency='--jobs=4 --output-sync=recurse'

$make $coefficiency

make: the '-j' option requires a positive integer argument


If I recall the offending command
  $make $coefficiency
, then place the cursor at the end of the line, and press Tab,
it expands to
  $make --jobs=4\ --output-sync=recurse
which seems to be the cause of this apparent anomaly: if I
then hit Enter, I get the same 'make' error message.

The space that's getting escaped is just a literal space:

$echo -n $coefficiency |od -t a

0000000   -   -   j   o   b   s   =   4  sp   -   -   o   u   t   p   u

0000020   t   -   s   y   n   c   =   r   e   c   u   r   s   e


Double-quoting the variable name doesn't help:

$make "$coefficiency" 2>&1 |head -1
make: the '-j' option requires a positive integer argument

I'm using this version of zsh:

$zsh --version

zsh 5.1.1 (i686-pc-cygwin)

and observe the same behavior with this version:

$zsh --version
zsh 4.3.17 (x86_64-unknown-linux-gnu)

I don't find any explanation of this behavior in the manual:
  http://zsh.sourceforge.net/Doc/Release/Prompt-Expansion.html
but I suppose that this behavior must be due to prompt expansion
because it works as I expect in a script:

$cat >eraseme.sh <<\EOF

heredoc> make $coefficiency

heredoc> EOF

$./eraseme.sh

echo  -j -Orecurse --jobserver-fds=3,4

-j -Orecurse --jobserver-fds=3,4