uiop/run-program:run-program regression after asdf-3.1.7

I try running (uiop/run-program:run-program '("where" "mvn.bat") :output
:string)

On asdf 3.1.7, it returns the correct output.

With asdf 3.1.7.27 and 3.1.7.43. I get an error "Class not found:
java.lang.UNIXProcess".
If I go to the top level, and try again, I get the correct result.

This is with:
C:\Users\977315>java -jar "c:\mv-program-files\abcl-bin-1.4.0\abcl.jar"
Armed Bear Common Lisp 1.4.0
Java 1.8.0_112 Oracle Corporation
Java HotSpot(TM) 64-Bit Server VM
Low-level initialization completed in 0.238 seconds.
Startup completed in 3.973 seconds.
Loading C:\Users\977315\.abclrc completed in 14.029 seconds.
Type ":help" for a list of available commands.
CL-USER(1):

The abclrc is minimal: load asdf and load quicklisp:

(eval-when (:compile-toplevel :load-toplevel :execute)
  (let ((file "asdf.3.1.7.43.lisp"))
    (load (merge-pathnames file
  (user-homedir-pathname)))))

(eval-when (:compile-toplevel :load-toplevel :execute)
  #-quicklisp
  (let ((quicklisp-init (merge-pathnames "quicklisp/setup.lisp"
(user-homedir-pathname))))
    (if (probe-file quicklisp-init)
(load quicklisp-init)
(error "Did not find ~a ... quicklisp not loaded"
"~/quicklisp/setup.lisp"))))

I posted this on the ASDF mailing list, and Fare suggested this may be an
ABCL-related
issue.

I hope all the problems I am having have one single root cause
- and that we discover it :-)