Python374-4.png shows that Tensorflow prints proper lines, ending with newline, when printing to the Windows console.  The 30 character progress bar is repeated on each new line.  It does not appear to be using either \r or \b.  I consider it a bug in tensorflow that it omits newlines when printing to IDLE, and that it apparently add \bs instead.

https://stackoverflow.com/questions/59309917/tensorflow-printing-weird-symbols-as is about the same issue.  The questioner ran 
 for c in '<boxes>': print(hex(ord(c)))
where <boxes> is the copy and pasted segment printing as the reverse bullets and they are indeed backspaces.  In his output, there are 39 backspaces, which is not at all enough to overprint the entire line.  This makes no sense to me.