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-rw-r--r--builtin/update-ref.c21
1 files changed, 17 insertions, 4 deletions
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 9046443..04dd00f 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -415,14 +415,27 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
die("%s: not a valid SHA1", value);
}
- hashclr(oldsha1); /* all-zero hash in case oldval is the empty string */
- if (oldval && *oldval && get_sha1(oldval, oldsha1))
- die("%s: not a valid old SHA1", oldval);
+ if (oldval) {
+ if (!*oldval)
+ /*
+ * The empty string implies that the reference
+ * must not already exist:
+ */
+ hashclr(oldsha1);
+ else if (get_sha1(oldval, oldsha1))
+ die("%s: not a valid old SHA1", oldval);
+ }
if (no_deref)
flags = REF_NODEREF;
if (delete)
- return delete_ref(refname, oldval ? oldsha1 : NULL, flags);
+ /*
+ * For purposes of backwards compatibility, we treat
+ * NULL_SHA1 as "don't care" here:
+ */
+ return delete_ref(refname,
+ (oldval && !is_null_sha1(oldsha1)) ? oldsha1 : NULL,
+ flags);
else
return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
flags | create_reflog_flag,