For some read Sysinternals junction utility doesn't show the raw substitute name. Microsoft's fsutil shows the actual reparse data:

    C:\>mklink /J Python34 "C:\Program Files\Python34"
    Junction created for Python34 <<===>> C:\Program Files\Python34

    C:\>fsutil reparsepoint query Python34
    Reparse Tag Value : 0xa0000003
    Tag value: Microsoft
    Tag value: Name Surrogate
    Tag value: Mount Point
    Substitue Name offset: 0
    Substitue Name length: 58
    Print Name offset:     60
    Print Name Length:     50
    Substitute Name:       \??\C:\Program Files\Python34
    Print Name:            C:\Program Files\Python34

    Reparse Data Length: 0x00000078
    Reparse Data:
    0000:  00 00 3a 00 3c 00 32 00  5c 00 3f 00 3f 00 5c 00  ..:.<.2.\.?.?.\.
    0010:  43 00 3a 00 5c 00 50 00  72 00 6f 00 67 00 72 00  C.:.\.P.r.o.g.r.
    0020:  61 00 6d 00 20 00 46 00  69 00 6c 00 65 00 73 00  a.m. .F.i.l.e.s.
    0030:  5c 00 50 00 79 00 74 00  68 00 6f 00 6e 00 33 00  \.P.y.t.h.o.n.3.
    0040:  34 00 00 00 43 00 3a 00  5c 00 50 00 72 00 6f 00  4...C.:.\.P.r.o.
    0050:  67 00 72 00 61 00 6d 00  20 00 46 00 69 00 6c 00  g.r.a.m. .F.i.l.
    0060:  65 00 73 00 5c 00 50 00  79 00 74 00 68 00 6f 00  e.s.\.P.y.t.h.o.
    0070:  6e 00 33 00 34 00 00 00                           n.3.4...

fsutil reparsepoint:
http://technet.microsoft.com/en-us/library/cc785451.aspx