commit - 381be7cc5b9b3d938b44f0f30dafdecf1c2f5a6b
commit + 49520a3227e82d18f80658e593e3300434fa8625
blob - 238a09f448842b25d1bc93a4f00809127c47e8a7
blob + 00586f45a6454992ba9f574c4bd6e54132bcda79
--- got/got.c
+++ got/got.c
@@ -283,6 +283,11 @@ cmd_checkout(int argc, char *argv[])
 	if (error != NULL)
 		goto done;
 
+	if (strcmp(path_prefix, got_worktree_get_path_prefix(worktree)) != 0) {
+		error = got_error(GOT_ERR_PATH_PREFIX);
+		goto done;
+	}
+
 	error = got_worktree_checkout_files(worktree, repo,
 	    checkout_progress, worktree_path, checkout_cancel, NULL);
 	if (error != NULL)
blob - e7d37e6ced26afc644b84a7fc0cd12c351b63596
blob + 7720ed223a4d642bf1479c1aed2af411b2dadc87
--- include/got_error.h
+++ include/got_error.h
@@ -67,6 +67,7 @@
 #define GOT_ERR_FILEIDX_SIG	51
 #define GOT_ERR_FILEIDX_VER	52
 #define GOT_ERR_FILEIDX_CSUM	53
+#define GOT_ERR_PATH_PREFIX	54
 
 static const struct got_error {
 	int code;
@@ -122,6 +123,8 @@ static const struct got_error {
 	{ GOT_ERR_FILEIDX_SIG,	"bad file index signature" },
 	{ GOT_ERR_FILEIDX_VER,	"unknown file index format version" },
 	{ GOT_ERR_FILEIDX_CSUM,	"bad file index checksum" },
+	{ GOT_ERR_PATH_PREFIX,	"worktree already contains items from a "
+				"different path prefix" },
 };
 
 /*
blob - aa7c545c7fa2e55ec8ce54f936a4e7138510a161
blob + 80de9bdeca406f8d4266ddd4b98a8a26f59d6df5
--- include/got_worktree.h
+++ include/got_worktree.h
@@ -47,6 +47,12 @@ void got_worktree_close(struct got_worktree *);
 char *got_worktree_get_repo_path(struct got_worktree *);
 
 /*
+ * Get the path prefix associated with a worktree.
+ * The caller must dispose of it with free(3).
+ */
+const char *got_worktree_get_path_prefix(struct got_worktree *);
+
+/*
  * Get the name of a work tree's HEAD reference.
  * The caller must dispose of it with free(3).
  */
blob - 1a57978e5b801e3f05e7fc89d8229263b8f664cf
blob + c55f3e7519777cdce2a4f25c8e35006404281300
--- lib/worktree.c
+++ lib/worktree.c
@@ -374,6 +374,12 @@ char *
 got_worktree_get_repo_path(struct got_worktree *worktree)
 {
 	return strdup(worktree->repo_path);
+}
+
+const char *
+got_worktree_get_path_prefix(struct got_worktree *worktree)
+{
+	return worktree->repo_path;
 }
 
 char *