Improve SHA*E extension extraction code.

Filter out over-long "extensions" before stripping out non-alphanumerics
from them, so that eg "foo.ba__________r" is not considered a .bar
extension.

Backend/Hash.hs

@@ -101,8 +101,9 @@ selectExtension f
 	| otherwise = intercalate "." ("":es)
   where
 	es = filter (not . null) $ reverse $
-		take 2 $ takeWhile shortenough $
-		reverse $ split "." $ filter validInExtension $ takeExtensions f
+		take 2 $ map (filter validInExtension) $
+		takeWhile shortenough $
+		reverse $ split "." $ takeExtensions f
 	shortenough e = length e <= 4 -- long enough for "jpeg"
 
 {- A key's checksum is checked during fsck. -}

CHANGELOG

@@ -1,3 +1,9 @@
+git-annex (6.20160528) UNRELEASED; urgency=medium
+
+  * Improve SHA*E extension extraction code.
+
+ -- Joey Hess <id@joeyh.name>  Fri, 27 May 2016 13:12:48 -0400
+
 git-annex (6.20160527) unstable; urgency=medium
 
   * Split lines in the git-annex branch on \r as well as \n, to deal

doc/bugs/strips___95___from_extensions_in_E_backends__63__.mdwn

@@ -13,3 +13,5 @@ lrwxrwxrwx 1 yoh yoh 126 May 25 14:27 ds001_R1.1.0_raw.tgz -> .git/annex/objects
 """]]
 
 [[!meta author=yoh]]
+
+> [[fixed|done]] --[[Joey]]