What's the story behind the revision history of Go?

I noticed that the first 4 revisions f6182e5abf5e, b66d0bf8da3e, ac3363d7e788, 172d32922e72 of the Go source are all from long before Golang was even proposed, the oldest being from 1972. They are also all credited to Brian Kernighan of AWK-ward fame. They seem to be hello, world implementations in C. Is this an easter-egg or is there some practical purpose?

That thread mentions:

<!-- language-all: lang-c -->

> Homage, Easter egg, inside joke, take your pick :). Notice the authors of the commits in question too

Said thread references this commit as the starting point, but also points out to the actual first commit of the Golang project, with the first revision of the Go spec.

The (alleged) "author" of the four first commits is Brian Kernighan.
Rob Pike has worked with Brian in the 1980's, at Bell Labs, so this can be viewed as a reference to his professional origin.

The idea of this Easter egg is to illustrate an evolution of an Hello World program in C:

(See more with this recent GopherCon April 2014 talk hellogophers.slide - Rob Pike)

Hello, World

hg log -r 0:4
changeset:   0:f6182e5abf5e
user:        Brian Kernighan <bwk>
date:        Tue Jul 18 19:05:45 1972 -0500
summary:     hello, world

$ hg update -r 0
$ cat src/pkg/debug/macho/testdata/hello.b

main( ) {
    extrn a, b, c;
    putchar(a); putchar(b); putchar(c); putchar('!*n');
}
a 'hell';
b 'o, w';
c 'orld';

Convert to C

changeset:   1:b66d0bf8da3e
user:        Brian Kernighan <bwk>
date:        Sun Jan 20 01:02:03 1974 -0400
summary:     convert to C

$ hg update -r 1
$ cat src/pkg/debug/macho/testdata/hello.c

main() {
    printf("hello, world");
}

Convert to Draft-Proposed ANSI C

changeset:   2:ac3363d7e788
user:        Brian Kernighan <research!bwk>
date:        Fri Apr 01 02:02:04 1988 -0500
summary:     convert to Draft-Proposed ANSI C

$ hg update -r 2
$ cat src/pkg/debug/macho/testdata/hello.c

#include <stdio.h>

main()
{
    printf("hello, world\n");
}

Last-minute fix: convert to ANSI C

changeset:   3:172d32922e72
user:        Brian Kernighan <bwk@research.att.com>
date:        Fri Apr 01 02:03:04 1988 -0500
summary:     last-minute fix: convert to ANSI C

$ hg update -r 3
cat src/pkg/debug/macho/testdata/hello.c


#include <stdio.h>

int
main(void)
{
    printf("hello, world\n");
    return 0;
}

Go spec starting point

changeset:   4:4e9a5b095532
user:        Robert Griesemer <gri@golang.org>
date:        Sun Mar 02 20:47:34 2008 -0800
summary:     Go spec starting point.