[PATCH] Add binary version to cache path to avoid multiple chicken installations using the same location

I don't know whether this patch is needed at all, maybe chicken-install detects differing versions of eggs automagically? I'm not familiar with its internals – but I have multiple chicken versions installed alongside each other and noticed that they all use the same ~/.cache/chicken-install/ directory. This patch makes chicken 6 instead use ~/.cache/chicken-install/12/, which is also future-proof for changing binary-version values.
I'm not sure how to get the email service I use to work with git, so I am attaching a plain diff below and as a MIME attachment.
diff --git a/egg-environment.scm b/egg-environment.scm
index ee68df7c..77e14299 100644
--- a/egg-environment.scm
+++ b/egg-environment.scm
@@ -123,7 +123,9 @@ EOF
       (string-append (or (system-cache-directory)
                           (current-directory))
                      "/"
-                      chicken-install-program)))
+                      chicken-install-program
+                      "/"
+                      (number->string binary-version))))
 
(define cache-metadata-directory
   ;; Directory where the VERSION, TIMESTAMP and STATUS files are

diff --git a/egg-environment.scm b/egg-environment.scm
index ee68df7c..77e14299 100644
--- a/egg-environment.scm
+++ b/egg-environment.scm
@@ -123,7 +123,9 @@ EOF
       (string-append (or (system-cache-directory)
                           (current-directory))
                      "/"
-                      chicken-install-program)))
+                      chicken-install-program
+                      "/"
+                      (number->string binary-version))))
 
 (define cache-metadata-directory
   ;; Directory where the VERSION, TIMESTAMP and STATUS files are