Make the ncurses unicode check earlier

and improve the message.

src/core/core.py

@@ -494,19 +494,6 @@ class Core(object):
         Init curses, create the first tab, etc
         """
         self.stdscr = curses.initscr()
-        if not hasattr(self.stdscr, 'get_wch'):
-            curses.echo()
-            curses.endwin()
-            print('ERROR: The current python executable is linked with a '
-                  'ncurses version with no unicode capabilities.\nThis'
-                  ' means python was built on a system where readline'
-                  ' is linked against libncurses and not libncursesw.\n'
-                  'Please file a bug for your distribution or recompile'
-                  ' libreadline with -ltermcapw instead of -ltermcap, '
-                  'and then recompile python.\nPoezio is currently unable'
-                  ' to read your input or draw its interface properly, so'
-                  ' it will now exit.')
-            self.exit()
         self.init_curses(self.stdscr)
         self.call_for_resize()
         default_tab = tabs.RosterInfoTab()

src/poezio.py

@@ -19,6 +19,29 @@ sys.path.append(os.path.dirname(os.path.abspath(__file__)))
 
 import singleton
 
+def test_curses():
+    """
+    Check if the system ncurses linked with python has unicode capabilities.
+    """
+    import curses
+    if hasattr(curses, 'unget_wch'):
+        return True
+    print("""\
+ERROR: The current python executable is linked with a ncurses version that \
+has no unicode capabilities.
+
+This could mean that:
+    - python was built on a system where readline is linked against \
+libncurses and not libncursesw
+    - python was built without ncursesw headers available
+
+Please file a bug for your distribution or fix that on your system and then \
+recompile python.
+Poezio is currently unable to read your input or draw its interface properly,\
+ so it will now exit.""")
+    return False
+
+
 def main():
     """
     Enter point
@@ -75,4 +98,7 @@ def main():
         pass
 
 if __name__ == '__main__':
-    main()
+    if test_curses():
+        main()
+    else:
+        sys.exit(1)