Revert "get_sha1_basic(): corner case ambiguity fix"

This reverts 6677c4665a commit.

The misguided disambiguation has been reverted, so there is no point
testing that misfeature.

sha1_name.c

@@ -223,7 +223,7 @@ static int ambiguous_path(const char *path, int len)
 			slash = 0;
 			continue;
 		}
-		return slash;
+		break;
 	}
 	return slash;
 }

t/t0000-basic.sh

@@ -205,52 +205,4 @@ test_expect_success \
     'no diff after checkout and git-update-index --refresh.' \
     'git-diff-files >current && cmp -s current /dev/null'
 
-
-# extended sha1 parsing and ambiguity resolution
-
-GIT_AUTHOR_DATE='1995-01-29T16:00:00 -0800'
-GIT_AUTHOR_EMAIL=a.u.thor@example.com
-GIT_AUTHOR_NAME='A U Thor'
-GIT_COMMITTER_DATE='1995-01-29T16:00:00 -0800'
-GIT_COMMITTER_EMAIL=c.o.mmitter@example.com
-GIT_COMMITTER_NAME='C O Mmitter'
-export GIT_AUTHOR_DATE
-export GIT_AUTHOR_EMAIL
-export GIT_AUTHOR_NAME
-export GIT_COMMITTER_DATE
-export GIT_COMMITTER_EMAIL
-export GIT_COMMITTER_NAME
-
-test_expect_success \
-	'initial commit.' \
-	'commit=$(echo Initial commit | git-commit-tree $tree) &&
-	 echo "$commit" >.git/refs/heads/master &&
-	 git-ls-tree HEAD &&
-	 test "$commit" = 51a092e9ef6cbbe66d258acd17599d3f80be6162'
-
-test_expect_success \
-	'Ambiguous' \
-	'echo "$commit" >.git/refs/heads/nasty &&
-	 echo "$commit" >.git/refs/tags/nasty &&
-	 if git-rev-parse --verify nasty
-	 then
-		echo "should have barfed"
-		false
-	 else
-	 	:
-	 fi &&
-	 # names directly underneath .git/ should not interfere
-	 echo "$commit" >.git/refs/heads/description &&
-	 git-rev-parse --verify description &&
-	 # broken object name
-	 echo fffffffffffffffffffffffffffffffffffffffg \
-	 	>.git/refs/heads/nasty &&
-	 if git-rev-parse --verify nasty
-	 then
-		echo "should have barfed"
-		false
-	 else
-	 	:
-	 fi'
-
 test_done