Avoid backtraces on expected failures when built with ghc 8; only use backtraces for unexpected errors.

ghc 8 added backtraces on uncaught errors. This is great, but git-annex was
using error in many places for a error message targeted at the user, in
some known problem case. A backtrace only confuses such a message, so omit it.

Notably, commands like git annex drop that failed due to eg, numcopies,
used to use error, so had a backtrace.

This commit was sponsored by Ethan Aubin.

1 files changed, 1 insertions, 1 deletions

diff --git a/Annex/Init.hs b/Annex/Init.hs
index 5aff4cf39..8a208fe2b 100644
--- a/Annex/Init.hs
+++ b/Annex/Init.hs
@@ -129,7 +129,7 @@ ensureInitialized = getVersion >>= maybe needsinit checkUpgrade
   where
 	needsinit = ifM Annex.Branch.hasSibling
 			( initialize Nothing Nothing
-			, error "First run: git-annex init"
+			, giveup "First run: git-annex init"
 			)
 
 {- Checks if a repository is initialized. Does not check version for ugrade. -}