That originated as a change from:

    if (explicit)
        stio->lines = 0;
[download]

to:

    if (explicit) {
        io->lines = 0;
        io->page = 0;
        io->lines_left = io->page_len;
    }
[download]

made public as:

commit 79072805bf63abe5b5978b5928ab00d360ea3e7f
Author: Larry Wall <lwall@netlabs.com>
Date:   Thu Oct 7 23:00:00 1993 +0000

    perl 5.0 alpha 2

    [editor's note: from history.perl.org.  The sparc executables
    originally included in the distribution are not in this commit.]

433 files changed, -41401 +64754 lines
[download]

You could search for a usenet report of some bug relatively soon before that timestamp.

Resetting $- on explicit close certainly "makes sense". Depending on your particular use case, I can also see it making sense to skip TOP after an explicit close() and then re-use of the same file handle.