Did the upgrade on my testforum, after initial testing all seems to work very well on 7.1.1, and a blank error log :O)
One funny thing, maintenance mode shows a double 'login' (firefox), don't think I've seen that before :O)
see attach.
Confirmed, also in IE11.
I see that an input slip in the last replace in the Login.template.php
<input type="hidden" name="', $context['session_var'], '" value="', $context['session_id'], '" /><p class="centertext"><input type="submit" value="', $txt['login'], '" class="button_submit" /><input type="hidden" name="hash_passwrd" value="" />
</div>
</form>';
Should be:
<input type="hidden" name="', $context['session_var'], '" value="', $context['session_id'], '" /><p class="centertext"><input type="hidden" name="hash_passwrd" value="" />
</div>
</form>';
<input type="hidden" name="', $context['session_var'], '" value="', $context['session_id'], '" />
<input type="hidden" name="hash_passwrd" value="" />
2.0.14, 7.1.1 and now https, things works (but Like Posts mod problem -posted in mod support), error log blank, but feeling not yet ready to change things on main forum.
After further testing on the test-forum, things looked good so applied 2.0.14 + php 7.0.15 to main forum.
All seemingly went very well. https at a later date.