git, hg: Use full revision

Before, the revision was at most the first 8 bytes in the revision. This
can be problematic for reproducibility since the revision may then be
ambiguous.

Author: reynir

src/repository/opamGit.ml

@@ -159,10 +159,7 @@ module VCS : OpamVCS.VCS = struct
        match r.OpamProcess.r_stdout with
        | []      -> Done None
        | full::_ ->
-         if String.length full > 8 then
-           Done (Some (String.sub full 0 8))
-         else
-           Done (Some full))
+         Done (Some full))
 
   let clean repo_root =
     git repo_root [ "clean"; "-fdx" ]

src/repository/opamHg.ml

@@ -53,8 +53,7 @@ module VCS = struct
     match r.OpamProcess.r_stdout with
     | [] -> Done None
     | full::_ ->
-      if String.length full > 8 then Done (Some (String.sub full 0 8))
-      else Done (Some full)
+      Done (Some full)
 
   let clean repo_root =
     hg repo_root ["revert"; "--all"; "--no-backup"]