Chat collapses white space
Expected: The game will be able to display multiple spaces in a row.
Actuality: The game only reads one space, even when multiple were entered. The dev console also displays only one space.
Created Issue:
Space Character Display Problem
Expected: The game will be able to display multiple spaces in a row.
Actuality: The game only reads one space, even when multiple were entered. The dev console also displays only one space.
Added Affects Versions: 14w11b
Changed Summary:
Space Character Reading ProblemChat collapses white space
Added Affects Versions: 1.7.8
Added Affects Versions: 14w17a
Added Affects Versions: 14w18b

Try /tellraw and surround the text by quotes.
Tellraw does the same, try with
/tellraw @a {text="abc abc a b c"}