shelve: delete shelve statefile on any exception during abort

When a user's repository is in an unfinished unshelve state and they choose to
abort, at a minimum, the repo should be out of that state. We've found
situations where the user could not leave the state unless manually deleting the
state file. This fix ensures that no matter what exception may be raised during
the abort, the shelved state file will be deleted, the user will be out of the
unshelve state and they can get their repository into a workable condition.

hgext/shelve.py

@@ -482,9 +482,9 b' def unshelveabort(ui, repo, state, opts)'
         mergefiles(ui, repo, state.wctx, state.pendingctx)
 
         repair.strip(ui, repo, state.stripnodes, backup=False, topic='shelve')
+    finally:
         shelvedstate.clear(repo)
         ui.warn(_("unshelve of '%s' aborted\n") % state.name)
-    finally:
         lockmod.release(lock, wlock)
 
 def mergefiles(ui, repo, wctx, shelvectx):

tests/test-shelve.t

@@ -1010,3 +1010,43 b' with general delta'
   changegroup -- "{'version': '02'}"
       7e30d8ac6f23cfc84330fd7e698730374615d21a
   $ cd ..
+
+test Abort unshelve always gets user out of the unshelved state
+---------------------------------------------------------------
+  $ hg init salvage
+  $ cd salvage
+  $ echo 'content' > root
+  $ hg commit -A -m 'root' -q
+  $ echo '' > root
+  $ hg shelve -q
+  $ echo 'contADDent' > root
+  $ hg unshelve -q
+  warning: conflicts while merging root! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
+  [1]
+Wreak havoc on the unshelve process
+  $ rm .hg/unshelverebasestate
+  $ hg unshelve --abort
+  unshelve of 'default' aborted
+  abort: No such file or directory
+  [255]
+Can the user leave the current state?
+  $ hg up -C .
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+Try again but with a corrupted shelve state file
+  $ hg strip -r 2 -r 1 -q
+  $ hg up -r 0 -q
+  $ echo '' > root
+  $ hg shelve -q
+  $ echo 'contADDent' > root
+  $ hg unshelve -q
+  warning: conflicts while merging root! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
+  [1]
+  $ sed 's/ae8c668541e8/123456789012/' .hg/shelvedstate > ../corrupt-shelvedstate
+  $ mv ../corrupt-shelvedstate .hg/histedit-state
+  $ hg unshelve --abort |& grep 'rebase aborted'
+  rebase aborted
+  $ hg up -C .
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved