bug#32978: 26.1; newline-and-indent duplicates displayed image

[Markus Triska]

Please download test.png from:

    https://www.metalevel.at/ei/test.png

and then invoke Emacs as follows:

    $ emacs -Q --eval='(progn (insert-image-file "test.png")
                              (forward-char)
                              (newline-and-indent))'

As a result, test.png is displayed twice, both in line 1 and in line 2.

In this case, I expect test.png to be displayed only in line 1.

In GNU Emacs 26.1 (build 1, i686-pc-linux-gnu, X toolkit, Xaw scroll bars)
 of 2018-05-29 built on debian
Repository revision: 07f8f9bc5a51f5aa94eb099f3e15fbe0c20ea1ea
Windowing system distributor 'The X.Org Foundation', version 11.0.11902000
System Description:     Debian GNU/Linux 9.2 (stretch)