ui: pass ' ' to raw_input when prompting

This is a workaround for calling ui.prompt(...), typing some character then
hitting backspace which causes the entire line to delete rather than just the
one character. This was seen on Debian using gnome-terminal.

(credits to Mads for the idea)

Python bug can be found here: http://bugs.python.org/issue12833

mercurial/ui.py

@@ -544,7 +544,7 b' class ui(object):'
         # instead of trying to emulate raw_input, swap self.fin with sys.stdin
         old = sys.stdin
         sys.stdin = self.fin
-        line = raw_input()
+        line = raw_input(' ')
         sys.stdin = old
 
         # When stdin is in binary mode on Windows, it can cause
@@ -561,7 +561,7 b' class ui(object):'
             self.write(msg, ' ', default, "\n")
             return default
         try:
-            r = self._readline(self.label(msg, 'ui.prompt') + ' ')
+            r = self._readline(self.label(msg, 'ui.prompt'))
             if not r:
                 return default
             return r