Description of problem:
When installing Fedora on a system with msdos label and two existing primary partitions and when using LVM, the /boot is created as a primary partition but instead of writing the LVM PV on a primary partition, an extended partition with a single logical partition (on which the LVM PV is written) is created.

As three partitions (the two pre-existing ones plus the newly created /boot) exist, the last partition is created as extended in order to allow the creation of more (logical) partitions.

This behaviour is correct, except when there is only one last partition to create (the fourth) and 100% of the disk is used (the user will therefore never be able to create any more logical partition anyway). The last partition should in this case simply be created as a primary partition (the fourth and last).

Alternatively, the user should be offered the option to create the LVM PV as primary partition (instead of a logical partition inside an extended partition).

Version-Release number of selected component (if applicable):
Current Fedora 22 net install.

How reproducible:
Always.

Steps to Reproduce:
1. Take an system with two existing primary partitions
2. Install Fedora with one /boot partition and everything else on LVM

Actual results:
sda
├─sda1  (existing primary partition)
├─sda2  (existing primary partition)
├─sda3  (/boot,   primary partition)
└─sda4  (newly created extended partition, containing...)
  └─sda5  (... a single logical partition hosting the LVM PV)
    ├─... (LVM LVs)

The extended partition will never contain more than a single logical partition, which is useless.

Expected results:
sda
├─sda1  (existing primary partition)
├─sda2  (existing primary partition)
├─sda3  (/boot,   primary partition)
└─sda4  (LVM PV,  primary partition)
  ├─... (LVM LVs)

Additional info: