pkgconf-2.2.0: not using more modules from [list of modules]

[art-latal]

Unexpected behaviour change between versions 1.6.3 and 2.2.0 when using --print-requires argument with multiple modules. Seems that behaviour changed when version 2.X was introduced. There was no change to man pages, which leads me to conclusion that this is unwanted regression.

Wrong behaviour:

$ pkg-config --version
2.2.0

$ pkg-config --print-requires atk
glib-2.0 >= 2.67.4
gobject-2.0 >= 2.0.0

$ pkg-config --print-requires atspi-2
dbus-1 >= 1.5
glib-2.0 >= 2.67.4

$ pkg-config --print-requires atk atspi-2
glib-2.0 >= 2.67.4
gobject-2.0 >= 2.0.0

^^^ here is missing print-requires for atspi-2

Correct behaviouir (with old version):

$ pkg-config --version
1.6.3

$ pkg-config --print-requires atk atspi-2
glib-2.0 >= 2.38.0
gobject-2.0 >= 2.38.0
dbus-1
glib-2.0

Reproducible: Always

(original report was filed on Gentoo Bugzilla bug 939814)