pathname.rb: fix a Pathname#relative_path_from crash on

* ext/pathname/lib/pathname.rb (SAME_PATHS):
  Pathname#relative_path_from uses String#casecmp to compare strings
  on case-insensitive filesystem platforms (e.g., Windows). This can
  return nil for strings with different encodings, and the code
  previously assumed that it always returned a Fixnum.  [Fix GH-713]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47591 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 1 deletions

diff --git a/ext/pathname/lib/pathname.rb b/ext/pathname/lib/pathname.rb
index e61aa2c081..82541e9b15 100644
--- a/ext/pathname/lib/pathname.rb
+++ b/ext/pathname/lib/pathname.rb
@@ -22,7 +22,8 @@ class Pathname
   end
 
   SAME_PATHS = if File::FNM_SYSCASE.nonzero?
-    proc {|a, b| a.casecmp(b).zero?}
+    # Avoid #zero? here because #casecmp can return nil.
+    proc {|a, b| a.casecmp(b) == 0}
   else
     proc {|a, b| a == b}
   end