Demonstrate exclude compose bug

Author: LMG

tests/filter/exclude_compose.t

@@ -0,0 +1,72 @@
+  $ export TESTTMP=${PWD}
+
+  $ cd ${TESTTMP}
+  $ git init real_repo 1> /dev/null
+  $ cd real_repo
+
+  $ mkdir sub1
+  $ echo contents1 > sub1/file1
+  $ git add sub1
+  $ git commit -m "add file1" 1> /dev/null
+
+  $ mkdir sub2
+  $ echo contents1 > sub2/file2
+  $ git add sub2
+  $ git commit -m "add file2" 1> /dev/null
+
+  $ josh-filter -s :exclude[:/sub2] master --update refs/heads/hidden
+  [1] :exclude[:/sub2]
+  [2] :/sub2
+  $ git checkout hidden 1> /dev/null
+  Switched to branch 'hidden'
+  $ tree
+  .
+  `-- sub1
+      `-- file1
+  
+  1 directory, 1 file
+  $ git log --graph --pretty=%s
+  * add file1
+
+  $ echo contents3 > sub1/file3
+  $ git add sub1/file3
+  $ git commit -m "add sub1/file3" 1> /dev/null
+
+  $ josh-filter -s :exclude[:/sub1,:/sub2] master --update refs/josh/filtered
+  [1] :/sub1
+  [1] :exclude[
+      :/sub1
+      :/sub2
+  ]
+  [1] :exclude[:/sub2]
+  [2] :/sub2
+  [2] :[
+      :/sub1
+      :/sub2
+  ]
+
+  $ git checkout refs/josh/filtered
+  Note: switching to 'refs/josh/filtered'.
+  
+  You are in 'detached HEAD' state. You can look around, make experimental
+  changes and commit them, and you can discard any commits you make in this
+  state without impacting any branches by switching back to a branch.
+  
+  If you want to create a new branch to retain commits you create, you may
+  do so (now or later) by using -c with the switch command. Example:
+  
+    git switch -c <new-branch-name>
+  
+  Or undo this operation with:
+  
+    git switch -
+  
+  Turn off this advice by setting config variable advice.detachedHead to false
+  
+  HEAD is now at bb282e9 add file1
+  $ tree
+  .
+  `-- sub1
+      `-- file1
+  
+  1 directory, 1 file