Extra undesirable space in between neumes that have [alt:] text

[jakubjelinek]

name:Angelus Domini;
office-part:Antiphona;
mode:6;
book:Cantus selecti, 1957, p. 278_;
transcriber:markM;
%%
(c4) AN([alt:i]f)ge([alt:i]f_e)lus([alt:i]dc) Dó([alt:i]f)mi([alt:i]fgd)ni([alt:i]ixf!gwhih.) (;)
nun([alt:i]j)ti([alt:i]ixih//)á([alt:i]gh)vit([alt:i]f) Ma([alt:i]f.g!hwiHG'F)rí([alt:i]ghf)æ.([alt:i]f.) V/(::)
Et([alt:i]f) con([alt:i]f)cé([alt:i]gh)pit([alt:i]f') (,)
de([alt:i]f) Spí([alt:i]g)ri([alt:i]f_e)tu([alt:i]dc) Sánc([alt:i]fgd)to.([alt:i]ixf!gwhih.) (::)

used to look 4 months ago like:

which has similar spacing to when the [alt:i] is removed from everywhere:

But with 20150429 develop branch (haven't tried release-3.0 yet), I get instead:

which has much more spacing around and many more scores are justified (so that additional spacing is probably rubber space).
nabc uses the same macro as [alt:], but needs extra patches.
Is there a way to get the old behavior, or adjust the extra spacing, or is this just a bug?
I'm not talking about the cases when the alt text runs into another alt text, just would like significantly less amount of extra spacing in there, so for most scores whether they have nabc neumes (or alt text) doesn't really affect the density of the notes in the score.

[jakubjelinek]

Also of interest is that with the [alt:i] and recent gregorio, most of the vowels are not aligned below the first note of the neume but somewhat to the left of it, while with [alt:i] removed (or with older gregorio) it is (or used to be) aligned properly.
Just for completeness, here is the 20150429 develop version of the score with all [alt:i] snippets removed: