bug#27115: Infinite loop created by fixing 26097

[Codrut Gusoi <codrut.gusoi@gmail.com>]

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Hello,

After bug 26097 was fixed I started using emacs built from soruce from
the master branch. There I encountered a but that only recently I
traced back to 8275687bb908174b84021ee15ecd959733cecb9d with a git
bisect.

Here are some high level details:

1) I am using Spacemacs
(https://github.com/sdwolf/spacemacs/tree/develop) with evil and helm.
2) I have linum active.
3) I press "M-x" which is bound to (helm-M-x). This opens helm and
triggers something called "Auto Evilification". Somewhere in this
process the following message is displayed:

```
Auto-evilification could not remap these functions in map ‘edebug-mode-map’:
   - ‘edebug-Go-nonstop-mode’ originally mapped on ‘G’
```

This is a single string with multiple "\n" inside it that can be
generated by the following code (extracted from Spacemacs):

```
(setq my-map-symbol 'edebug-mode-map)
(setq my-pending-funcs '((edebug-Go-nonstop-mode . 71)))
(message (concat (format (concat "Auto-evilification could not remap
these " "functions in map `%s': \n") my-map-symbol) (mapconcat (lambda
(x) (format " - `%s' originally mapped on `%s'" (car x)
(single-key-description (cdr x)))) my-pending-funcs "\n")))
```

4) After the above message is displayed emacs freezes.
5) If i do a "pkill -USR2 emacs" I get a backtrace that looks like the
attached file. I can not paste it because it contains some nulls (^@)
and it gets truncated.

6) I did a git bisect and it led me to this commit:
8275687bb908174b84021ee15ecd959733cecb9d, the first attempt at fixing
26097, later edited by a749b55d8ee530797ccff693ad302541257d0415.

7) If I remove the "\n" from the message, making it a single line, the
problem no longer appears. Also if I disable linum in the currently
open buffer then there is no problem with the multi line message.

Here is a reference to the github issue in which I, and a few more
people discuss about this bug.

I can provide a VM for you to ssh into and reproduce the bug with my
setup. Just email me privately so I can give you the ssh details. Also
let me know if you need any more details from me. I will try to answer
as quickly as possible.

Thank you,
Codrut

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