If I use a colored prompt (like the default one), long lines don't wrap correctly, I can't see what I typed any more after the line wrapped and backspace behaves weird. If I remove the color from $PS1, bash behaves correctly again. I remember having a colored prompt without these problems in an older gentoo-install, so either somethin in the ebuild changed or the bash breaks. This unwanted behavior is really annoying.
*** Bug 72548 has been marked as a duplicate of this bug. ***
rebuild bash