When I updated my iTerm2 recently in November (the main release, not nightly-build), colors are rendered strange. Fortunately, I restored old iTerm2 in the trash can, and made a comparison.
In each of the four pictures, the left penal is a tex file, the right a cpp file, and the terminal's theme is always Tango dark, with no additional alteration. In such order, they are: October iTerm2 with "default" color of vim's; October iTerm2 with "koehler" color of vim's; November iTerm2 with "default" color of vim's; November iTerm2 with "koehler" color of vim's.
Compared with the 1st picture, I am sure the 3rd picture has something wrong, but the 2nd and 4th are similar. So it seems the "default" scheme of vim is rendered incorrectly, and I found that it is not the only color scheme affected, like "desert" is also different, but I am not going to post so many pictures here for sake of space.
So, is it true that iTerm2 makes some mistake in interpreting vim's color settings? If it doesn't, why is 1st and 3rd pictures so different, and what's wrong? If it does, is there some way to make iTerm2 apply correct color for "default" in the old manner, since I like it (1st picture, right panel). You might think me fussy, but I use vim in iTerm2 every day. Or the best advice for me is that I never shall update and stick to old iTerm2 from now on?