guix package: Inherit the transformed version number.

Previously, 'guix package -i emacs --with-source=./emacs-42.tar.gz'
would fail to use "42" as the version number in the manifest entry.

Reported by piyo on #guix.

* guix/scripts/package.scm (process-actions)[transform-entry]: Inherit
the version number from the result of TRANSFORM when it's a package.
* tests/guix-package.sh: Test it.

guix/scripts/package.scm

@@ -794,9 +794,13 @@ processed, #f otherwise."
   (define transform (options->transformation opts))
 
   (define (transform-entry entry)
-    (manifest-entry
-      (inherit entry)
-      (item (transform store (manifest-entry-item entry)))))
+    (let ((item (transform store (manifest-entry-item entry))))
+      (manifest-entry
+        (inherit entry)
+        (item item)
+        (version (if (package? item)
+                     (package-version item)
+                     (manifest-entry-version entry))))))
 
   ;; First, process roll-backs, generation removals, etc.
   (for-each (match-lambda

tests/guix-package.sh

@@ -140,6 +140,20 @@ rm "$profile" "$profile"-[0-9]-link
 guix gc -d "$real_profile"
 [ ! -d "$real_profile" ]
 
+# Package transformations.
+
+# Make sure we get the right version number when using '--with-source'.
+mkdir "$module_dir"
+emacs_tarball="$module_dir/emacs-42.5.9rc7.tar.gz"
+touch "$emacs_tarball"
+guix package -p "$profile" -i emacs --with-source="$emacs_tarball" -n \
+     2> "$tmpfile"
+grep -E 'emacs[[:blank:]]+42\.5\.9rc7[[:blank:]]+.*-emacs-42.5.9rc7' \
+     "$tmpfile"
+rm "$emacs_tarball" "$tmpfile"
+rmdir "$module_dir"
+
+
 #
 # Try with the default profile.
 #