Revert "Update tslib.pyx"

This reverts commit 40ac031.

Author: sumitbinnani

pandas/tslib.pyx

@@ -3230,10 +3230,6 @@ cpdef inline int64_t cast_from_unit(object ts, object unit) except? -1:
     cdef:
         int64_t m
         int p
-        
-    if unit == 'julian':
-        unit = 'D'
-        ts = ts - Timestamp(0).to_julian_date()
 
     if unit == 'D' or unit == 'd':
         m = 1000000000L * 86400