migration with `-replicas` option > 1 creates as many replicas as there are pools

[DmitryLitvintsev]

Demonstration:

# ssh -p 22224 [email protected] "\s w-cmsstor708-disk-disk2 migration copy -tmode=cached -select=random -pnfsid=00007202AED0F7DC45F2B399CAE2297DCAF1 -replicas=2 -target=pgroup flushPools"
[5] INITIALIZING migration copy -tmode=cached -select=random -pnfsid=00007202AED0F7DC45F2B399CAE2297DCAF1 -replicas=2 -target=pgroup -- flushPools

[# ssh -p 22224 [email protected] "\sl 00007202AED0F7DC45F2B399CAE2297DCAF1 rep ls 00007202AED0F7DC45F2B399CAE2297DCAF1"
w-cmsstor708-disk-disk2:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[1]> 2490786864 si={cms.cms11}
w-cmsstor905-disk-disk3:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C----------L(0)[0]> 2490786864 si={cms.cms11}

# ssh -p 22224 [email protected] "\sl 00007202AED0F7DC45F2B399CAE2297DCAF1 rep ls 00007202AED0F7DC45F2B399CAE2297DCAF1"
w-cmsstor201-disk-disk2:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[0]> 2490786864 si={cms.cms11}
w-cmsstor708-disk-disk2:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[1]> 2490786864 si={cms.cms11}
w-cmsstor905-disk-disk3:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C----------L(0)[0]> 2490786864 si={cms.cms11}
w-cmsstor920-disk-disk4:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[0]> 2490786864 si={cms.cms11}

# ssh -p 22224 [email protected] "\sl 00007202AED0F7DC45F2B399CAE2297DCAF1 rep ls 00007202AED0F7DC45F2B399CAE2297DCAF1"
w-cmsstor106-disk-disk3:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[0]> 2490786864 si={cms.cms11}
w-cmsstor201-disk-disk2:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[0]> 2490786864 si={cms.cms11}
w-cmsstor708-disk-disk2:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[1]> 2490786864 si={cms.cms11}
w-cmsstor905-disk-disk3:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C----------L(0)[0]> 2490786864 si={cms.cms11}
w-cmsstor920-disk-disk4:
    00007202AED0F7DC45F2B399CAE2297DCAF1 <C-------X--L(0)[0]> 2490786864 si={cms.cms11}