Fix from_man_exp to correctly reject non-integral mantissa

This partially reverts 25506567

mpmath/ctx_mp_python.py

@@ -64,7 +64,7 @@ class _mpf(mpnumeric):
             if len(val) == 4:
                 val = val[0], MPZ(val[1]), *val[2:]
             elif len(val) == 2:
-                v._mpf_ = from_man_exp(MPZ(val[0]), val[1], prec, rounding)
+                v._mpf_ = from_man_exp(val[0], val[1], prec, rounding)
                 return v
             else:
                 raise ValueError

mpmath/libmp/libmpf.py

@@ -8,7 +8,7 @@ import re
 import sys
 import warnings
 
-from .backend import BACKEND, MPZ, MPZ_FIVE, MPZ_ONE, MPZ_ZERO, gmpy
+from .backend import BACKEND, MPZ, MPZ_FIVE, MPZ_ONE, MPZ_ZERO, gmpy, int_types
 from .libintmath import (bctable, bin_to_radix, isqrt, numeral, sqrtrem,
                          stddigits, trailtable)
 
@@ -204,7 +204,10 @@ def normalize(sign, man, exp, bc, prec, rnd):
 def from_man_exp(man, exp, prec=0, rnd=round_fast):
     """Create raw mpf from (man, exp) pair. The mantissa may be signed.
     If no precision is specified, the mantissa is stored exactly."""
-    man = MPZ(man)
+    if isinstance(man, int_types):
+        man = MPZ(man)
+    else:
+        raise TypeError("man expected to be an integer")
     sign = 0
     if man < 0:
         sign = 1

mpmath/tests/test_basic_ops.py

@@ -685,3 +685,8 @@ def test_rounding_prop():
     assert mp.sin(1) == mpf('0x1.aed548f090cefp-1')
     with pytest.raises(ValueError):
         mp.rounding = 'x'
+
+
+def test_from_man_exp():
+    with pytest.raises(TypeError):
+        mp.mpf(("!", 1))