Issue #7384: On Gentoo, libreadline.so is a "fake library", so ldd fails.

In that case, do not attempt to parse stderr output.

setup.py

@@ -594,7 +594,10 @@ class PyBuildExt(build_ext):
         # Determine if readline is already linked against curses or tinfo.
         if do_readline and find_executable('ldd'):
             fp = os.popen("ldd %s" % do_readline)
-            for ln in fp:
+            ldd_output = fp.readlines()
+            ret = fp.close()
+            if ret is None or ret >> 8 == 0:
+                for ln in ldd_output:
                     if 'curses' in ln:
                         readline_termcap_library = re.sub(
                             r'.*lib(n?cursesw?)\.so.*', r'\1', ln
@@ -603,7 +606,6 @@ class PyBuildExt(build_ext):
                     if 'tinfo' in ln: # termcap interface split out from ncurses
                         readline_termcap_library = 'tinfo'
                         break
-            fp.close()
         # Issue 7384: If readline is already linked against curses,
         # use the same library for the readline and curses modules.
         if 'curses' in readline_termcap_library: