Bug#926598: xmlstarlet fo --omit-decl exits with non-zero code

[Etienne Dechamps]

Package: xmlstarlet
Version: 1.6.1-2

Steps to reproduce:

$ echo '<A/>' | xmlstarlet fo --omit-decl; echo $?

Expected result:

<A/>
0

Actual result:

<A/>
5

What's really weird is that the returned error code is always
identical to the number of bytes written to the output.

This bug seems to only occur if --omit-decl is used.