I just sat down and decided to write the bit of code that decides how much
you have to download and how much space it will take to install those
downloads when I noticed that dpkg does not store the Installed-Size field
in the status file.
This basically means it's pointless to try and figure out the amount of
space required to upgrade a package! I can tell you how much space the new
version will take but without the amount of space that the old version is
taking the figure is meaningless.
The only way to get this information is to scan the info dir and read the
size of ever file on the disk and regenerate the Installed-Size field.
Since dpkg --info shows the Installed-Size field I can only assume it is
an oversight in dpkg not to include the information in the status file.
What should we do?