diff -r 1855b5c3da61 Lib/pydoc.py
--- a/Lib/pydoc.py	Mon Nov 17 23:48:35 2014 +0200
+++ b/Lib/pydoc.py	Tue Nov 18 11:41:50 2014 +0200
@@ -1477,12 +1477,18 @@ def ttypager(text):
         old = tty.tcgetattr(fd)
         tty.setcbreak(fd)
         getchar = lambda: sys.stdin.read(1)
-    except (ImportError, AttributeError):
+    except (ImportError, AttributeError, io.UnsupportedOperation):
         tty = None
         getchar = lambda: sys.stdin.readline()[:-1][:1]
 
     try:
-        r = inc = os.environ.get('LINES', 25) - 1
+        try:
+            h = int(os.environ.get('LINES', 25))
+            if h <= 1:
+                h = 25
+        except ValueError:
+            h = 25
+        r = inc = h - 1
         sys.stdout.write('\n'.join(lines[:inc]) + '\n')
         while lines[r:]:
             sys.stdout.write('-- more --')