Hanging when process writing into pipe has exited

[i-ky]

I use the command like this one:

$ ./my_script.py 2>&1 | colout -t cmake | colout -t g++ | colout -s Xml

Sometimes this command hangs. In the process list I don't see my_script, only colout processes:

develop+ 14887  0.0  0.0  12664  3068 pts/4    S+   14:17   0:00 /bin/bash /usr/local/bin/colout -t cmake
develop+ 14888  0.0  0.0  12664  3080 pts/4    S+   14:17   0:00 /bin/bash /usr/local/bin/colout -t g++
develop+ 14889  0.0  0.0  12664  2972 pts/4    S+   14:17   0:00 /bin/bash /usr/local/bin/colout -s Xml
develop+ 14890  0.2  0.4  59708 22988 pts/4    S+   14:17   0:00 python3 -m colout.colout -t cmake
develop+ 14891  0.2  0.4  59848 23324 pts/4    S+   14:17   0:00 python3 -m colout.colout -t g++
develop+ 14892  0.2  0.4  59704 23060 pts/4    S+   14:17   0:00 python3 -m colout.colout -s Xml

Doing

$ sudo strace -p 14890

reveals that this process is doing read(0.

colout was installed from GitHub. OS is Ubuntu 16.04.