unexpected linebreak disappears when I add a manual linebreak

[bwl21]

I:measurenb 1
I:staffnonote 2
%I:linebreak $
% --------------
X:1
F:1_3010measurenumber
T:measure-number
C:
S:
M:4/4
L:1/4
Q:1/4=120
K:C
%
%
%%score 1
%
V:1 clef=treble name="Sopran" snm="S"
CCCC | DD::DD |1 EEEE |2 DDED || (3EEEeEE | EEEE

Yields

but when I add a linebreak in the source before the "|1"

% - settings to improve Handling in Zupfnoter
I:measurenb 1
I:staffnonote 2
%I:linebreak $
% --------------
X:1
F:1_3010measurenumber
T:measure-number
C:
S:
M:4/4
L:1/4
Q:1/4=120
K:C
%
%
%%score 1
%
V:1 clef=treble name="Sopran" snm="S"
CCCC | DD::DD 
|1 EEEE |2 DDED || (3EEEeEE | EEEE

I get it in one line

[bwl21]

I could safely reproduce it with 1.15.3.

I tried again with 1.15.4. Now it works as expected.
The first example now yields one line. The second example now yields two lines

Maybe it was fixed with #62. I you find this reasonable, we can close this.

[moinejf]

Indeed, #62 fixed a lot of bad cases. Anyway, as for #64, the most important is that the problem disappeared.

[bwl21]

so I close this as well.