network-manager: fix getting of ifname from the sysfs path
    
    commit 5e0f8c8a4ced ('network-manager: remove useless use of basename')
    somewhat carelessly didn't take into account that $_i has a slash at
    the end which made the result of the ## substitution be just an empty
    string.
    
    The slash was put to the end of /sys/class/net/*/ to make sure we're only
    iterating directories, but it's not strictly necessary. In an unlikely case
    something else than a directory appears in /sys/class/net/, we'll already deal
    with it gracefully. Remove it.
    
    This fixes the TEST-30-ISCSI test.
    
    (cherry picked from commit 687e17aa7f2f40d21717be9a04302c749e139d4a)
    
    Resolves: #1826061
    
    patch_name: 0070.patch
    present_in_specfile: true
    location_in_specfile: 70
    squash_commits: true