Simplify ChangeLog entry for mbedtls_mpi_sub_abs fix.

Signed-off-by: Aaron M. Ucko <ucko@ncbi.nlm.nih.gov>
diff --git a/ChangeLog.d/conditionalize-mbedtls_mpi_sub_abs-memcpy.txt b/ChangeLog.d/conditionalize-mbedtls_mpi_sub_abs-memcpy.txt
index 564f9ac..0a90721 100644
--- a/ChangeLog.d/conditionalize-mbedtls_mpi_sub_abs-memcpy.txt
+++ b/ChangeLog.d/conditionalize-mbedtls_mpi_sub_abs-memcpy.txt
@@ -1,5 +1,4 @@
 Bugfix
-   * Fix mbedtls_mpi_sub_abs() to account for the possibility that the output
-     pointer could equal the first input pointer and if so to skip a memcpy()
-     call that would be redundant.  Reported by Pascal Cuoq using TrustInSoft
-     Analyzer in #6701; observed independently by Aaron Ucko under Valgrind.
+   * Fix potential undefined behavior in mbedtls_mpi_sub_abs().  Reported by
+     Pascal Cuoq using TrustInSoft Analyzer in #6701; observed independently by
+     Aaron Ucko under Valgrind.