Backport checkin:
Clarify the behaviour of PyUnicode_DecodeUTF16(): A BOM is only skipped
in native order mode, and only if it's the first two bytes.
diff --git a/Doc/api/concrete.tex b/Doc/api/concrete.tex
index e1f3e9a..8aa9b0f 100644
--- a/Doc/api/concrete.tex
+++ b/Doc/api/concrete.tex
@@ -1173,10 +1173,10 @@
*byteorder == 1: big endian
\end{verbatim}
- and then switches according to all byte order marks (BOM) it finds
- in the input data. BOMs are not copied into the resulting Unicode
- string. After completion, \var{*byteorder} is set to the current
- byte order at the end of input data.
+ and then switches if the first two bytes of the input data are a byte order
+ mark (BOM) and the specified byte order is native order. This BOM is not
+ copied into the resulting Unicode string. After completion, \var{*byteorder}
+ is set to the current byte order at the.
If \var{byteorder} is \NULL{}, the codec starts in native order mode.