bug#57272: libvirt 8.6 fails to start network

[Lars-Dominik Braun <lars@6xq.net>]

Hi,

after the update to libvirt 8.6.0 in
3a76c2bfd94557c9776aa11240fec14580aec1b0 networks don’t start any more:

    > LANG=C virsh net-start default
    error: Failed to start network default
    error: Unable to find 'dnsmasq' binary in $PATH: No such file or directory

I tried to patch dnsmasq’s path like follows, but then the testcase
networkxml2conftest fails and cannot find dnsmasq either.

---snip---
diff --git a/gnu/packages/virtualization.scm b/gnu/packages/virtualization.scm
index d451b8529e..89507774cb 100644
--- a/gnu/packages/virtualization.scm
+++ b/gnu/packages/virtualization.scm
@@ -1311,6 +1311,12 @@ (define-public libvirt
               (substitute* "scripts/meson-install-dirs.py"
                 (("destdir = .*")
                  "destdir = '/tmp'"))))
+          (add-after 'unpack 'fix-paths
+            (lambda* (#:key inputs #:allow-other-keys)
+              (let ((dnsmasq (search-input-file inputs "sbin/dnsmasq")))
+                (substitute* "src/util/virdnsmasq.c"
+                  (("#define DNSMASQ \"dnsmasq\"")
+                   (string-append "#define DNSMASQ \"" dnsmasq "\""))))))
           (add-before 'configure 'disable-broken-tests
             (lambda _
               (let ((tests (list "commandtest"         ; hangs idly
---snap---

I’m not sure what the problem might be.

Lars