See the build output at e.g.
https://perflab.isc.org/#/run/test/5803dec3d6cd1ce83eddd27e/

... gcc  -I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build
-I../.. -I./include
-I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/lib/dns/include
-I../../lib/dns/include
-I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/lib/bind9/include
-I../../lib/bind9/include
-I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/lib/isc/include
-I../../lib/isc -I../../lib/isc/include -I../../lib/isc/unix/include
-I../../lib/isc/pthreads/include -I../../lib/isc/x86_32/include
-I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/lib/lwres/include
-I../../lib/lwres/unix/include -I../../lib/lwres/include
-I/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/lib/isccfg/include
-I../../lib/isccfg/include  -D_REENTRANT -DVERSION=\"9.11.0\" -DOPENSSL
-D_GNU_SOURCE -g -O2 -I/usr/include/libxml2   -fPIC  -W -Wall
-Wmissing-prototypes -Wcast-qual -Wwrite-strings -Wformat
-Wpointer-arith -fno-strict-aliasing -fno-delete-null-pointer-checks  -c
nslookup.c
Makefile:230: recipe for target 'nslookup.o' failed
make[2]: Leaving directory
'/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/bin/dig'
Makefile:75: recipe for target 'subdirs' failed
make[1]: Leaving directory
'/home/perflab/data/tests/56b23423a2ef0a42e723c9d4/build/bin'
Makefile:83: recipe for target 'subdirs' failed

The only change I made that appears to have caused this is to install
libedit-devel (which also updated libncurses-devel) to support building
knot2.

It looks like it's probably affecting all branches, up to and including
master.

I've just removed libedit-devel and it seems to have fixed the build.

Ray