Arch Linux

I am currently doing a new install on one box.
So I start, select a french mirror : http://mir1.archlinuxfr.org/archlinux/iso/
Then prepare hard disk, then go to select and install packages.
Now the installer complains that it cannot fetch the database because the mirror is down.. BUT it does not allow me to go back to select another mirror. It just goes on with the next screen, which is an empty list of packages. I can just see "base". I press OK (again no other choice), and AIF eventually just dies with a confusing error message that I did not keep.

Now I start /arch/setup again, select a second french mirror hoping I will be more lucky.
Then I go directly to Step 4 : Select packages since I already did everything else. But aif complains telling me I need to prepare the hard drive first.. The fact is, the partitions were already made, the filesystems created and mounted.
I tried to only do the step "Manually configure block devices, filesystems and mountpoints" , it told me it detected all the partitions and asked if I wanted to use that. I went ahead. But then it tried to re-create all the filesystems (already mounted = fail), and to mount them again (second fail). So in the end, it considered the hard drive was still not prepared. And I was still completely stuck in the installer.

So I just looked up aif code, removed the dependency on step 3 to do step 4, and I am resuming the installation now.

So there was just one simple problem (mirror down) which highlighted many problems in cascade :
1) does not detect that a mirror is down / does not allow you to go back or select another mirror when fetching the database fails
2) cannot resume directly to Step 4 if it believes the hard disk is not prepared (while it actually is)
3) it does not detect that the hard disk is already prepared, and I did not find any manual way (in aif interface) to specify it