Description

Related to #3588, #3589 and #3590

When supplying a pipe to --json-pp scancode can hang and has to be interrupted.

How To Reproduce

$ mknod /tmp/bla/pipe p
$ time ./scancode -l scancode --json-pp /tmp/bla/pipe
Setup plugins...
Collect file inventory...
Scan files for: licenses with 1 process(es)...
[####################] 2                  
^CRemoving temporary files...done.

Aborted!
^C

real	0m25.566s
user	0m4.274s
sys	0m0.953s

System configuration

For bug reports, it really helps us to know:

• What OS are you running on? (Windows/MacOS/Linux)
• What version of scancode-toolkit was used to generate the scan file?
• What installation method was used to install/run scancode? (pip/source download/other)