Very frequently, libmicrohttpd freezes during the execution of make test,
showing something like this in the build log:

[  112s] make  check-TESTS
[  112s] make[3]: Entering directory
'/home/abuild/rpmbuild/BUILD/libmicrohttpd-0.9.50/src/microhttpd'
[  112s] make[4]: Entering directory
'/home/abuild/rpmbuild/BUILD/libmicrohttpd-0.9.50/src/microhttpd'
[  117s] PASS: test_shutdown_select
[  122s] PASS: test_shutdown_poll
[28931s] qemu-system-x86_64: terminating on signal 15 from pid 24017
[28931s] ### WATCHDOG MARKER END ###

As this package is part of ring1 and thus of full staging, it is often blocking
a staging project from moving on.. Usually retriggering it for build works -
but that can't be the solution