Potentially involved commits:

eeac677 (8.0.0754)
b41bf8e (8.0.0791)

I recent upgraded my FreeBSD 10.3 vim-lite package from 8.0.0742 to 8.0.0809 and was surprised to find that colours looked incorrect -- specifically, they were darker (i.e. bold bit no longer being set on terminal output).

FreeBSD's TERM=xterm uses t_Co=8 and has for decades. The terminal truly only supports 8 colours, but in the terminal emulator (PuTTY), bold being set causes the colours to be brighter. This behaviour is "ANSI-like" (where bold means "brighter colour" rather than a bolded font) and is extremely common.

I do not use t_Co=256 because the colours look weird to me ("washed out", purely an aesthetic dislike), and I do not use TERM=xterm-color (which uses t_Co=256 anyway) because not all *IX software works correctly with xterm-color.

Attached are screenshots of FreeBSD 10.3 vim-lite 8.0.0809 vs. FreeBSD 9.3 vim-lite 8.0.0134. There are irrelevant termcap differences (I reviewed them), but visually you can see the difference I'm referring to (re: lack of bold). FreeBSD binary package updates do not have have a native way to revert to a previous package, so I cannot roll back to 8.0.0742.

Crummy workaround, which may or not be accurate (can't tell if 0754 or 0791 is responsible):

if has("patch-8.0.0754") && &term =~ "xterm"
  set t_Co=16
endif