Fix ConfigVersion failure in release archive

#483 (comment).

src/dune

@@ -85,7 +85,7 @@
   (target configVersion.ml)
   (mode (promote (until-clean) (only configVersion.ml))) ; replace existing file in source tree, even if releasing (only overrides)
   (deps (universe)) ; do not cache, always regenerate
-  (action (pipe-stdout (run git describe --all --long --dirty) (with-stdout-to %{target} (bash "xargs printf '(* Automatically regenerated, changes do not persist! *)\nlet version = \"%s\"'")))))
+  (action (pipe-stdout (bash "git describe --all --long --dirty || echo \"n/a\"") (with-stdout-to %{target} (bash "xargs printf '(* Automatically regenerated, changes do not persist! *)\nlet version = \"%s\"'")))))
 
 (rule
   (target configProfile.ml)

src/version.ml

@@ -1,8 +1,16 @@
 let release = "%%VERSION_NUM%%"
+let release_commit = "%%VCS_COMMIT_ID%%"
 
 let goblint =
   let commit = ConfigVersion.version in
   if BatString.starts_with release "%" then
     commit
-  else
+  else (
+    let commit =
+      if commit = "n/a" then (* released archive has no .git *)
+        release_commit
+      else
+        commit
+    in
     Format.sprintf "%s (%s)" release commit
+  )