The password font is in a sans-serif style (in fact the entire Edit
Entry dialog window is in the same style).   This makes it impossibly
difficult to distinguish I from l (from |), not so helpful when the
password needs to be copied by hand.

I can change the setting in Tools -> Options -> Interface -> Select Password
font. The original value was Liberation Mono, I can change it to
Liberation Serif (or DejaVu Serif, or whatever).  But it makes no
difference to the font shown in Edit Entry (and in the password).

Indeed, this I/l problem should not exist in Liberation Mono in the
first place.  Something is wrong with the font handling.  The font set
in options is not the font used in Edit Entry or in the password box.

I even tried with and without the Advanced interface option "Force
using system font (Unix only)", but it makes no difference.

If I change "Select List Font", then I can see the font changing, but
only in the main KeePass window where the entries are listed (and even
then, the menus File,Edit,View,Tools remain in the same san-serif font
that I see in Edit Entry).

My desktop environment is Gnome 3.8, not sure if that's relevant.

I noticed this bug was happening on my Debian VM but not my desktop itself (also Debian). Both are running keepass2 version 2.19. Further investigation revealed the system NOT having the problem has the password font set to "Liberation Mono"

The above font wasn't even an option on the system having the problem. It was set to "DejaVu Sans Mono" which showed correctly in the preview but not in the actual password field. Instead it was using a font where an I looked like an l.

Further, after installing gimp, I noticed the problem went away. The font is now set to "Nimbus Mono L"

It looks like this package needs something in another package, and that other package isn't automatically included when installing this package.