Add a test for escaping of backslashes in list expansion

pylib/gyp/input.py

Index: pylib/gyp/input.py
===================================================================
--- pylib/gyp/input.py	(revision 1106)
+++ pylib/gyp/input.py	(working copy)
@@ -736,7 +736,7 @@
           output = replacement[:]
         else:
           # Split it the same way sh would split arguments.
-          output = shlex.split(str(replacement))
+          output = shlex.split(str(replacement).replace('\\', '\\\\'))

[Mark Mentovai, 2011/12/14 17:53:54]

Are you sure that this is right? Seems perverse. The backslash is very special
and this doesn’t account for all possibilities, like backslashes inside
single-quoted strings.
['ab', 'c', 'd\\e']
['a\\b', 'c', 'd\\\\e']

That’s kind of weird, don’t you agree?

[tony, 2011/12/14 18:41:39]

Backslash is only special when being passed to a command line.  This is just
variable expansion.  Shouldn't the special handling of backslash in single
quotes be handled when executing the command?

It's more weird that we escape backslash in list expansion, but not in non-list
expansion.

       else:
         # Expanding in string context.
         encoded_replacement = ''