[MC-111144] /stats does not find marker armorstands in upper half of a block

The second selector of the /stats entity command does not find marker armorstands that are in the upper half of a block when using r=0 or dy=?.

Steps to reproduce:

/scoreboard objectives add STATS_TEST dummy

/scoreboard objectives setdisplay sidebar STATS_TEST

/summon armor_stand ~ 57.6 ~ {Tags:["statsTest"],NoGravity:1,Marker:1}

/scoreboard players set @e[type=armor_stand,tag=statsTest] STATS_TEST 0

/stats entity @e[type=armor_stand,tag=statsTest] set SuccessCount @e[type=armor_stand,tag=statsTest,r=0,c=1] STATS_TEST

/execute @e[type=armor_stand,tag=statsTest] ~ ~ ~ testfor @p

After the execute-testfor command the armorstand should have a score of 1, but it has a score of 0. If I repeat the same experiment with other y values and other selectors instead of

r=0

there are the results:

	r=0	r=1	dy=0	dy=1
57.0
57.1
57.4
57.5
57.6
57.9

A useful command to get rid of all the Armorstands

/kill @e[type=armor_stand,tag=statsTest]

Here is a OneCommand that creates the setup

summon falling_block ~ ~1 ~ {Block:redstone_block,Time:1,Passengers:[{id:falling_block,Block:activator_rail,Time:1},{id:commandblock_minecart,Command:fill ~1 ~-2 ~1 ~4 ~-1 ~2 air},{id:commandblock_minecart,Command:setblock ~2 ~-2 ~2 command_block 5  {Command:scoreboard objectives add STATS_TEST dummy}},{id:commandblock_minecart,Command:setblock ~3 ~-2 ~2 chain_command_block 5  {auto:1,Command:scoreboard objectives setdisplay sidebar STATS_TEST}},{id:commandblock_minecart,Command:setblock ~4 ~-2 ~2 chain_command_block 1  {auto:1,Command:summon armor_stand ~ 57.6 ~ {Tags:["statsTest"],NoGravity:1,Marker:1}}},{id:commandblock_minecart,Command:setblock ~4 ~-1 ~2 chain_command_block 4  {auto:1,Command:scoreboard players set @e[type=armor_stand,tag=statsTest] STATS_TEST 0}},{id:commandblock_minecart,Command:setblock ~3 ~-1 ~2 chain_command_block 4  {auto:1,Command:stats entity @e[type=armor_stand,tag=statsTest] set SuccessCount @e[type=armor_stand,tag=statsTest,r=0,c=1] STATS_TEST}},{id:commandblock_minecart,Command:setblock ~2 ~-1 ~2 chain_command_block 4  {auto:1,Command:execute @e[type=armor_stand,tag=statsTest] ~ ~ ~ testfor @p}},{id:commandblock_minecart,Command:setblock ~ ~-2 ~ command_block},{id:commandblock_minecart,Command:setblock ~ ~2 ~ command_block 0  {Command:fill ~ ~-3 ~ ~ ~ ~ air}},{id:commandblock_minecart,Command:setblock ~ ~1 ~ redstone_block},{id:commandblock_minecart,Command:kill @e[type=commandblock_minecart,r=0]}]}