Created attachment 315337 [details]
mbox testcase, to reply to

evolution-3.18.2-1.fc23.x86_64

0. Use plain text format in mail composer
0. Have a mail signature defined
1. Import attached testcase
2. Open that email
3. Ctrl+R
4. Out of the three quoted lines you see, click into the middle one (empty)
   ❛foo ❜
5. Write:
   abc
6. Press Ctrl+Z

EXPECTED OUTCOME ("|" marks the cursor):

   On blah, foo wrote:
   > http://heise.de/foo-
   > ab|
   > andre
   -- 
   foo

ACTUAL OUTCOME ("|" marks the cursor):

   On blah, foo wrote:
   > ht|p://heise.de/foo-
   > abc
   > andre
   -- 
   foo