fast-export: --signed-commits is experimental

As the design of signature handling is still being discussed, it is
likely that the data stream produced by the code in Git 2.50 would
have to be changed in such a way that is not backward compatible.

Mark the feature as experimental and discourge its use for now.

Also flip the default on the generation side to "strip"; users of
existing versions would not have passed --signed-commits=strip and
will be broken by this change if the default is made to abort, and
will be encouraged by the error message to produce data stream with
future breakage guarantees by passing --signed-commits option.

As we tone down the default behaviour, we no longer need the
FAST_EXPORT_SIGNED_COMMITS_NOABORT environment variable, which was
not discoverable enough.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/Documentation/RelNotes/2.50.0.adoc b/Documentation/RelNotes/2.50.0.adoc
index c6c34d1a1d..9a1cdf0dc0 100644
--- a/Documentation/RelNotes/2.50.0.adoc
+++ b/Documentation/RelNotes/2.50.0.adoc
@@ -100,7 +100,9 @@ Performance, Internal Implementation, Development Support etc.
  * "git fsck" becomes more careful when checking the refs.
 
  * "git fast-export | git fast-import" learns to deal with commit and
-   tag objects with embedded signatures a bit better.
+   tag objects with embedded signatures a bit better.  This is highly
+   experimental and the format of the data stream may change in the
+   future without compatibility guarantees.
 
  * The code paths to check whether a refname X is available (by seeing
    if another ref X/Y exists, etc.) have been optimized.