Index: nix/test/common/mod.rs
===================================================================
--- nix.orig/test/common/mod.rs
+++ nix/test/common/mod.rs
@@ -135,8 +135,10 @@ cfg_if! {
                     // Fedora 33 reports version as 4.18.el8_2.x86_64 or
                     // 5.18.200-fc33.x86_64.  Remove the underscore.
                     .replace("_", "-")
-                    // Cirrus-CI reports version as 4.19.112+ .  Remove the +
-                    .replace("+", "");
+                    // Cirrus-CI reports version as 4.19.112+
+                    // Some debian test runners report versions like
+                    // 6.6.13+bpo-cloud-amd64, replace the + with a -
+                    .replace("+", "-");
                 let mut version = Version::parse(fixed_release).unwrap();
 
                 //Keep only numeric parts