task description gets truncated when using multibyte characters

When displaying reports, the task description gets truncated at the end by the number of multibyte characters in the description, when the task contains annotations and the description line is shorter than the annotation line.

Let me give an example session with german umlauts as multibyte characters (some unimportant lines deleted).

First we create and annotate a task without umlauts:

$ task add +test "abcdefg"
Created task 104.
$ task 104 annotate "bla foo bar"
Annotating task 104 'abcdefg'.
Annotated 1 task.
$ task +test
[task next ( +test )]

ID Age Tag Description Urg
104 12s test abcdefg 0
2019-09-15 bla foo bar

Everything is displayed fine. Now we add umlauts:

$ task 104 mod "äöü abcdefg"
Modifying task 104 'äöü abcdefg'.
Modified 1 task.
$ task +test
[task next ( +test )]

ID Age Tag Description Urg
104 28s test äöü abcd 0
2019-09-15 bla foo bar

The description line is truncated by the number of umlauts.
Now we add some fill characters so, that the description line
gets longer than the annotation line:

$ task 104 mod "äöü sssssssssssssss abcdefg"
Modifying task 104 'äöü sssssssssssssss abcdefg'.
Modified 1 task.
$ task +test
[task next ( +test )]

ID Age Tag Description Urg
104 1min test äöü sssssssssssssss abcdefg 0
2019-09-15 bla foo bar

The description line is not truncated anymore.
Let's adjust the number of fill characters:

$ task 104 mod "äöü ssssssssssss abcdefg"
Modifying task 104 'äöü ssssssssssss abcdefg'.
Modified 1 task.
$ task +test
[task next ( +test )]

ID Age Tag Description Urg
104 1min test äöü ssssssssssss abcdefg 0
2019-09-15 bla foo bar

It still works. Remove one more fill character:

$ task 104 mod "äöü sssssssssss abcdefg"
Modifying task 104 'äöü sssssssssss abcdefg'.
Modified 1 task.
$ task +test
[task next ( +test )]

ID Age Tag Description Urg
104 1min test äöü sssssssssss abcd 0
2019-09-15 bla foo bar

The end characters get truncated again.

And finally, the output of "task diag":

$ task diag

task 2.5.1
Platform: Linux

Compiler
Version: 7.2.0
Caps: +stdc +stdc_hosted +LP64 +c8 +i32 +l64 +vp64 +time_t64
Compliance: C++11

Build Features
CMake: 3.9.5
libuuid: libuuid + uuid_unparse_lower
libgnutls: 3.5.8
Build type: None

Configuration
File: /home/cs/.taskrc (found), 3529 bytes, mode 100644
Data: /home/cs/.task (found), dir, mode 40755
Locking: Enabled
GC: Enabled
Server:
CA: /home/cs/.task/ca.cert.pem, readable, 3731 bytes
Trust: ignore hostname
Certificate: /home/cs/.task/client.cert.pem, readable, 3714 bytes
Key: /home/cs/.task/client.key.pem, readable, 24742 bytes
Ciphers: NORMAL
Creds: PRIV/cs/************************************

Hooks
System: Enabled
Location: /home/cs/.task/hooks
(-none-)

Tests
$TERM: xterm-256color (323x70)
Dups: Scanned 176 tasks for duplicate UUIDs:
No duplicates found
Broken ref: Scanned 176 tasks for broken references:
No broken references found