bug#36516: Wrong dynamic abbrev expansion after space

[Juri Linkov]

0. emacs -Q
1. Type these two lines:
str 1
str 2
2. On the third line type:
 s                      ;; self-insert-command
 t                      ;; self-insert-command
 r                      ;; self-insert-command
 SPC                    ;; self-insert-command
 M-/                    ;; dabbrev-expand
 M-/                    ;; dabbrev-expand
3. The result is correct, the third line is correctly expanded to:
str 1

Now the test case that exposes the error:

0. emacs -Q
1. Type these two lines:
str 1
str 2
2. On the third line type:
 s                      ;; self-insert-command
 M-/                    ;; dabbrev-expand
 SPC                    ;; self-insert-command
 M-/                    ;; dabbrev-expand
 M-/                    ;; dabbrev-expand
3. The word after "str " is expanded to some random word.