gitview: import only one of gtksourceview and gtksourceview2

Importing both gtksourceview and gtksourceview2 will make python segfault
on my system (ubuntu 7.10). Change so that gtksourceview is only imported
if importing gtksourceview2 fails. This should be safe as gtksourceview
is only used if gtksourceview2 is not available.

Signed-off-by: Anton Gyllenberg <anton@iki.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/gitview/gitview

@@ -27,20 +27,17 @@ import math
 import string
 import fcntl
 
+have_gtksourceview2 = False
+have_gtksourceview = False
 try:
     import gtksourceview2
     have_gtksourceview2 = True
 except ImportError:
-    have_gtksourceview2 = False
-
-try:
-    import gtksourceview
-    have_gtksourceview = True
-except ImportError:
-    have_gtksourceview = False
-
-if not have_gtksourceview2 and not have_gtksourceview:
-    print "Running without gtksourceview2 or gtksourceview module"
+    try:
+        import gtksourceview
+        have_gtksourceview = True
+    except ImportError:
+        print "Running without gtksourceview2 or gtksourceview module"
 
 re_ident = re.compile('(author|committer) (?P<ident>.*) (?P<epoch>\d+) (?P<tz>[+-]\d{4})')