fix windows assistant upgrade glitch

Prevent windows assistant from trying (and failing) to upgrade itself,
which has never been supported on windows.

The new windows build is made with UPGRADE_LOCATION set, which enabled this
code path that had never run on windows before, and doesn't work. I don't
want to try to support self-upgrade on windows, or generally on other OS's
than the ones where its working, so added a check for that. This way the
build can keep setting UPGRADE_LOCATION and if some later git-annex does
learn how to upgrade itself on some OS, it won't need changing the build
setup.

Assistant/Threads/Upgrader.hs

@@ -31,7 +31,7 @@ import qualified Data.Text as T
 
 upgraderThread :: UrlRenderer -> NamedThread
 upgraderThread urlrenderer = namedThread "Upgrader" $
-	when (isJust BuildInfo.upgradelocation) $ do
+	when upgradeSupported $ do
 		{- Check for upgrade on startup, unless it was just
 		 - upgraded. -}
 		unlessM (liftIO checkSuccessfulUpgrade) $

Assistant/Upgrade.hs

@@ -338,6 +338,18 @@ distributionInfoUrl = fromJust BuildInfo.upgradelocation ++ ".info"
 distributionInfoSigUrl :: String
 distributionInfoSigUrl = distributionInfoUrl ++ ".sig"
 
+{- Upgrade only supported on linux and OSX. -}
+upgradeSupported :: Bool
+#ifdef linux_HOST_OS
+upgradeSupported = isJust BuildInfo.upgradelocation
+#else
+#ifdef darwin_HOST_OS
+upgradeSupported = isJust BuildInfo.upgradelocation
+#else
+upgradeSupported = False
+#endif
+#endif
+
 {- Verifies that a file from the git-annex distribution has a valid
  - signature. Pass the detached .sig file; the file to be verified should
  - be located next to it.

Assistant/WebApp/Configurators/Preferences.hs

@@ -21,7 +21,7 @@ import Annex.NumCopies
 import Utility.DataUnits
 import Git.Config
 import Types.Distribution
-import qualified BuildInfo
+import Assistant.Upgrade
 
 import qualified Data.Text as T
 import qualified System.FilePath.ByteString as P
@@ -59,7 +59,7 @@ prefsAForm d = PrefsForm
 		, ("disabled", NoAutoUpgrade)
 		]
 	autoUpgradeLabel
-		| isJust BuildInfo.upgradelocation = "Auto upgrade"
+		| upgradeSupported = "Auto upgrade"
 		| otherwise = "Auto restart on upgrade"
 
 	positiveIntField = check isPositive intField

CHANGELOG

@@ -13,6 +13,8 @@ git-annex (8.20201117) UNRELEASED; urgency=medium
     the stderr pipe to it was left open, due to a daemon having inherited
     the file descriptor.
   * Fix build on Windows.
+  * Prevent windows assistant from trying (and failing) to upgrade
+    itself, which has never been supported on windows.
 
  -- Joey Hess <id@joeyh.name>  Mon, 16 Nov 2020 09:38:32 -0400
 

doc/bugs/Upgrader_crashed.mdwn

@@ -37,3 +37,6 @@ Upgrader crashed: C:\Users\alexasus\.config\git-annex\program: openFile: does no
 I've barely just installed. So I'm gonna get going these days. That warning doesn't seem to be an issue so far. I've looked it up but couldn't find any other reports for that warning.
 
 
+
+> [[fixed|done]] (by skipping checking upgrades on OS's where it's not
+> supported) --[[Joey]]