BUG: fix issue with distutils.exec_command introduced in 1.7.0.

Closes numpygh-2999 and numpygh-2915.

There are several packages (nose, scipy.weave.inline, Sage inline Fortran) that
replace stdout, in which case it doesn't have a fileno method.  This method was
attempted to be used (change in numpygh-2766 to fix a py3k issue).

numpy/distutils/exec_command.py

@@ -195,7 +195,8 @@ def exec_command( command,
         # _exec_command_posix uses os.system and is faster
         # but not on all platforms os.system will return
         # a correct status.
-        if _with_python and sys.stdout.fileno() == -1:
+        if _with_python and hasattr(sys.stdout, 'fileno') and \
+                            sys.stdout.fileno() == -1:
             st = _exec_command_python(command,
                                       exec_command_dir = exec_dir,
                                       **env)
@@ -349,12 +350,17 @@ def _exec_command( command, use_shell=None, use_tee = None, **env ):
                 argv = [os.environ['COMSPEC'],'/C'] + argv
                 using_command = 1
 
-    so_fileno = sys.stdout.fileno()
-    se_fileno = sys.stderr.fileno()
-    so_flush = sys.stdout.flush
-    se_flush = sys.stderr.flush
-    so_dup = os.dup(so_fileno)
-    se_dup = os.dup(se_fileno)
+    _has_fileno = hasattr(sys.stdout, 'fileno')
+    if _has_fileno:
+        so_fileno = sys.stdout.fileno()
+        se_fileno = sys.stderr.fileno()
+        so_flush = sys.stdout.flush
+        se_flush = sys.stderr.flush
+        so_dup = os.dup(so_fileno)
+        se_dup = os.dup(se_fileno)
+    else:
+        so_flush = sys.stdout.flush
+        se_flush = sys.stderr.flush
 
     outfile = temp_file_name()
     fout = open(outfile,'w')
@@ -371,13 +377,16 @@ def _exec_command( command, use_shell=None, use_tee = None, **env ):
 
     so_flush()
     se_flush()
-    os.dup2(fout.fileno(),so_fileno)
-    if using_command:
-        #XXX: disabled for now as it does not work from cmd under win32.
-        #     Tests fail on msys
-        os.dup2(ferr.fileno(),se_fileno)
-    else:
-        os.dup2(fout.fileno(),se_fileno)
+    if _has_fileno:
+        os.dup2(fout.fileno(),so_fileno)
+
+    if _has_fileno:
+        if using_command:
+            #XXX: disabled for now as it does not work from cmd under win32.
+            #     Tests fail on msys
+            os.dup2(ferr.fileno(),se_fileno)
+        else:
+            os.dup2(fout.fileno(),se_fileno)
     try:
         status = spawn_command(os.P_WAIT,argv0,argv,os.environ)
     except OSError:
@@ -387,8 +396,9 @@ def _exec_command( command, use_shell=None, use_tee = None, **env ):
 
     so_flush()
     se_flush()
-    os.dup2(so_dup,so_fileno)
-    os.dup2(se_dup,se_fileno)
+    if _has_fileno:
+        os.dup2(so_dup,so_fileno)
+        os.dup2(se_dup,se_fileno)
 
     fout.close()
     fout = open_latin1(outfile,'r')

numpy/distutils/tests/test_exec_command.py

@@ -0,0 +1,29 @@
+import sys
+import StringIO
+
+from numpy.distutils import exec_command
+
+
+class redirect_stdout(object):
+    """Context manager to redirect stdout for exec_command test."""
+    def __init__(self, stdout=None):
+        self._stdout = stdout or sys.stdout
+
+    def __enter__(self):
+        self.old_stdout = sys.stdout
+        sys.stdout = self._stdout
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self._stdout.flush()
+        sys.stdout = self.old_stdout
+
+
+def test_exec_command():
+    # Regression test for gh-2999 and gh-2915.
+    # There are several packages (nose, scipy.weave.inline, Sage inline
+    # Fortran) that replace stdout, in which case it doesn't have a fileno
+    # method.  This is tested here, with a do-nothing command that fails if the
+    # presence of fileno() is assumed in exec_command.
+    with redirect_stdout(StringIO.StringIO()):
+        exec_command.exec_command("cd '.'")
+