Why is 'ls' suddenly wrapping items with spaces in single quotes?

I just noticed that on one of my machines (running Debian Sid) whenever I type ls any file name with spaces has single quotes surrounding it.

I immediately checked my aliases, only to find them intact.

wyatt@debian630:~/testdir$ ls
'test 1.txt'  test1.txt
wyatt@debian630:~/testdir$ alias
alias ls='ls --color=auto'
alias wget='wget --content-disposition'
wyatt@debian630:~/testdir$

(picture)

Another test, with files containing single quotes in their names (also answering a request by jimmij):

wyatt@debian630:~/testdir$ ls
'test 1.txt'  test1.txt  'thishasasinglequotehere'\''.txt'
wyatt@debian630:~/testdir$ touch "'test 1.txt'"
wyatt@debian630:~/testdir$ ls
''\''test 1.txt'\'''  test1.txt
'test 1.txt'          'thishasasinglequotehere'\''.txt'

(picture)

update with new coreutils-8.26 output (which is admittedly much less confusing, but still irritating to have by default). Thanks to Pádraig Brady for this printout:

$ ls
"'test 1.txt'"   test1.txt
'test 1.txt'    "thishasasinglequotehere'.txt"

$ ls -N
'test 1.txt'  test1.txt
test 1.txt    thishasasinglequotehere'.txt

Why is this happening? How do I stop it properly?

to clarify, I myself set ls to automatically color output. It never put quotes around things before.

I'm running bash and coreutils 8.25.

EDIT: Appears the coreutils developers thought (link) it would be a good idea to make that a global default despite breaking the principle of least astonishment as well as 46+ years of UNIX tradition.

Any way to fix this without a recompile?

---

UPDATE - October 2017 - Debian Sid has re-enabled the shell escape quoting by default. This is just getting ridiculous. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=877582

And at the bottom of the reply chain to the previous bug report, "the change was intentional and will remain." https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=813164#226

I thought this was settled. Apparently not.

UPDATE: April 2019: Just found a supurious bug report in PHP that was caused by this change to ls. When you're confusing developers and generating false bug reports, it's time to re-think your changes.

Update: Android toybox ls is now doing something similar to this but with backslashes instead of quotes. Using the -q option makes spaces render as 'question mark characters' (I have not checked what they are, since they're obviously not spaces), so the only fix I have found so far without rooting the device in question is to add this to a script and source it when launching a shell. This function makes ls use columns if in a terminal and otherwise print one-per-line, while tricking ls into printing spaces verbatim because it's running through a pipe.

ls() {
    # only way I can stop ls from escaping with backslashes
    if [ -t 1 ]; then
        /system/bin/ls -C "$@" |cat
    else
        /system/bin/ls "$@" |cat
    fi
}