Spaces lost between words with text markup

Ubuntu 14.04, GIT commit: 0f698fd

First reported in https://musescore.org/en/node/48296#comment-347751, then with more detail in https://musescore.org/en/node/75806.

Steps to reproduce:

1) My First Score, edit title to "Title Two" (optionally use multiple spaces between the two words to make the bug more obvious)
2) Using the text toolbar, make the word "Title" italic, the word "Two" bold, leaving the space normal
2) save
3) close
4) reload

Result: the space is gone

This was originally reported in conjunction with a dynamic marking that was edited to read "poco f", with the word "poco" in italics, and the "f" is represented using "sym" tags (dynamicForte).

As far as I can tell, this issue only happens if the text before and after the space *both* have markup.

I am marking this "major" as there is loss of information.