`dune subst` can add a duplicate version field in opam

[samoht]

It seems that jbuilder subst doesn't check if a version field is already present in the opam file before adding a new one. It should either: don't add a new field of already present or (probably better) replace the field with some new contents.

To reproduce:

$ cat foo.opam
version: "foo"
$ jbuilder subst
$ git diff
diff --git a/foo.opam b/foo.opam
index d228968..3711f0d 100644
--- a/foo.opam
+++ b/foo.opam
@@ -1 +1,2 @@
+version: "34185ff"
 version: "foo"

there is also this 3rd option: if the version is present in the opam file, use it rather than call git describe ...

[samoht]

Yea I am not sure... /cc @Drup who is putting version field in his opam files :-)

I also created #880 to discuss these versions problems. Currently it's not clear to me what Dune should do regarding versions.

[Drup]

there is also this 3rd option: if the version is present in the opam file, use it rather than call git describe ...

Well, no. The version I put in the opam file in my dev repositories is "dev". I don't want that in the release.