Merge branch 'pg/maint-1.7.9-am-where-is-patch' into maint

When "git am" failed, old timers knew to check .git/rebase-apply/patch
to see what went wrong, but we never told the users about it.

* pg/maint-1.7.9-am-where-is-patch:
  am: indicate where a failed patch is to be found

Documentation/config.txt

@@ -176,6 +176,9 @@ advice.*::
 		Advice shown when you used linkgit:git-checkout[1] to
 		move to the detach HEAD state, to instruct how to create
 		a local branch after the fact.
+	amWorkDir::
+		Advice that shows the location of the patch file when
+		linkgit:git-am[1] fails to apply it.
 --
 
 core.fileMode::

git-am.sh

@@ -855,6 +855,11 @@ did you forget to use 'git add'?"
 	if test $apply_status != 0
 	then
 		eval_gettextln 'Patch failed at $msgnum $FIRSTLINE'
+		if test "$(git config --bool advice.amworkdir)" != false
+		then
+			eval_gettextln "The copy of the patch that failed is found in:
+   $dotest/patch"
+		fi
 		stop_here_user_resolve $this
 	fi