shelve: don't crash on file with unexpected extension in .hg/shelved/

We assumed that the files in the `.hg/shelved/` directory have an
extension. That's a valid assumption except that users may put garbage
in the directory. This patch fixes the crash by simply not assuming
that the result of splittin a string at '.' yields an extension. We
don't use the extension since the previous patch anyway.

Differential Revision: https://phab.mercurial-scm.org/D9720

mercurial/shelve.py

@@ -625,7 +625,7 b' def listshelves(repo):'
     info = []
     seen = set()
     for (filename, _type) in names:
-        name, ext = filename.rsplit(b'.', 1)
+        name = filename.rsplit(b'.', 1)[0]
         if name in seen:
             continue
         seen.add(name)

tests/test-shelve2.t

@@ -779,10 +779,10 b' Test corrupt shelves (in .hg/shelved/, n'
 
 # A file with an unexpected extension
   $ touch .hg/shelved/junk3
-  $ hg shelve -l 2>&1 | grep ValueError
-  ValueError: not enough values to unpack (expected 2, got 1)
-  $ hg unshelve 2>&1 | grep ValueError
-  ValueError: not enough values to unpack (expected 2, got 1)
+  $ hg shelve -l
+  $ hg unshelve
+  abort: no shelved changes to apply!
+  [20]
   $ hg shelve -d junk3
   abort: shelved change 'junk3' not found
   [10]