evolution-3.18.2-1.fc23.x86_64

0. Use plain text format in mail composer
0. Have a mail signature defined
0. Copy some long URL into the clipboard, like
   https://help.gnome.org/users/evolution/3.18/mail-organizing.whatever.html.en
1. Open new mail composer window, go to mail body
2. Write this (ignore the ❛❜ markers, just using them to make spaces clear):
   ❛foo ❜
3. Paste that long URL
4. Write this (ignore the ❛❜ markers, just using them to make spaces clear):
   ❛ lalala❜
5. Press Ctrl+Z

EXPECTED OUTCOME ("|" marks the cursor):

foo https://help.gnome.org/users/evolution/3.18/mail-organizing.whateve
r.html.en lalal|

ACTUAL OUTCOME ("|" marks the cursor):

foo https://help.gnome.org/users/evolution/3.18/mail-
organizing.whatever.html.e| lalala