Looks like the date string parsing needs a look. Feel free to snag it, but I'll assign this one to myself for now.
ircwaves@nile:~$ gips_inventory Landsat -t 020031 -d 2006-04-01,2006-4-31
GIPS Data Inventory (v0.8.0rc4)
Data inventory error: invalid literal for int() with base 10: '01,2006'
Looks like the date string parsing needs a look. Feel free to snag it, but I'll assign this one to myself for now.