Setting opcache.enable=0 removed the ==> error_log <== zend_mm_heap corrupted. The install doesn't crash but continues to load the Moodle tables.
However, once the tables have loaded, the logic returns back to the original installation page.
==> access_log <==
[01/Mar/2018:17:16:56 +0000] "GET /moodle/admin/index.php?cache=0&lang=en&agreelicense=1 HTTP/1.1" 200 40021
[01/Mar/2018:17:16:57 +0000] "GET /moodle/lib/javascript.php?rev=-1&jsfile=%2Flib%2Fjavascript-static.js HTTP/1.1" 200 43659
[01/Mar/2018:17:16:57 +0000] "GET /moodle/lib/javascript.php?rev=-1&jsfile=%2Flib%2Frequirejs%2Frequire.min.js HTTP/1.1" 200 17739
[01/Mar/2018:17:16:57 +0000] "GET /moodle/theme/font.php?theme=boost&component=core&rev=1&font=fontawesome-webfont.woff2?v=4.7.0 HTTP/1.1" 200 77160
[01/Mar/2018:17:16:57 +0000] "GET /moodle/lib/requirejs.php?file=%2F-1%2F/core/first.js HTTP/1.1" 200 1770601
[01/Mar/2018:17:16:59 +0000] "GET /moodle/lib/javascript.php?file=%2F-1%2Flib/jquery/jquery-3.2.1.min.js HTTP/1.1" 200 86660
[01/Mar/2018:17:16:59 +0000] "GET /moodle/theme/yui_combo.php?m/-1/core/event/event-min.js HTTP/1.1" 200 393
[01/Mar/2018:17:25:05 +0000] "GET /moodle/lib/javascript.php?rev=-1&jsfile=%2Flib%2Fjavascript-static.js HTTP/1.1" 200 43659
[01/Mar/2018:17:25:04 +0000] "GET /moodle/admin/index.php?cache=0&agreelicense=1&confirmrelease=1&lang=en HTTP/1.1" 200 69234
All Moodle tables are successfully loaded after about 12 minutes.
[01/Mar/2018:17:37:24 +0000] "GET /moodle/lib/javascript.php/1519925842/lib/requirejs/require.min.js HTTP/1.1" 200 6531
[01/Mar/2018:17:37:25 +0000] "GET /moodle/lib/requirejs.php/1519925842/core/first.js HTTP/1.1" 200 125670
[01/Mar/2018:17:37:26 +0000] "GET /moodle/lib/javascript.php/1519925842/lib/jquery/jquery-3.2.1.min.js HTTP/1.1" 200 30081
[01/Mar/2018:17:37:27 +0000] "GET /moodle/theme/yui_combo.php?m/-1/core/event/event-min.js HTTP/1.1" 200 393
[01/Mar/2018:17:37:27 +0000] "POST /moodle/lib/ajax/service.php?sesskey=MzbTY1Ayx3&info=core_fetch_notifications HTTP/1.1" 200 239
I don't understand this line
[01/Mar/2018:17:39:01 +0000] "469" 400 226
Pressing continue here, once the tables successfully load.
[01/Mar/2018:17:39:48 +0000] "GET /moodle/admin/index.php?sessionstarted=1&lang=en HTTP/1.1" 200 25053
[01/Mar/2018:17:39:53 +0000] "GET /moodle/lib/javascript.php/1519925842/lib/javascript-static.js HTTP/1.1" 200 6748
[01/Mar/2018:17:39:53 +0000] "GET /moodle/theme/styles.php/boost/1519925842_1/all HTTP/1.1" 200 110091
[01/Mar/2018:17:40:04 +0000] "GET /moodle/theme/yui_combo.php?m/1519925842/core/event/event-min.js&m/1519925842/filter_mathjaxloader/loader/loader-min.js HTTP/1.1" 200 825
[01/Mar/2018:17:40:04 +0000] "GET /moodle/theme/yui_combo.php?3.17.2/event-mousewheel/event-mousewheel-min.js&3.17.2/event-resize/event-resize-min.js&3.17.2/event-hover/event-hover-min.js&3.17.2/event-touch/event-touch-min.js&3.17.2/event-move/event-move-min.js&3.17.2/event-flick/event-flick-min.js&3.17.2/event-valuechange/event-valuechange-min.js&3.17.2/event-tap/event-tap-min.js HTTP/1.1" 200 4808
[01/Mar/2018:17:40:04 +0000] "GET /moodle/theme/image.php/boost/theme/1519925842/favicon HTTP/1.1" 200 1150
[01/Mar/2018:17:40:04 +0000] "POST /moodle/lib/ajax/service.php?sesskey=GkjMqi3rQV&info=core_fetch_notifications HTTP/1.1" 200 239
Installation never progresses to the Admin page.