systemd: do not remove empty paths from unit lookup path

The ability to start a new unit with 'systemctl start ...' should not
depend on whether there are other units in the directory. Previously,
an additional 'systemctl daemon-reload' would be necessary to tell
systemd to update the list of unit lookup paths.

src/shared/path-lookup.c

@@ -316,7 +316,6 @@ int lookup_paths_init(
                 return -ENOMEM;
 
         strv_uniq(p->unit_path);
-        path_strv_remove_empty(p->unit_path);
 
         if (!strv_isempty(p->unit_path)) {
 
@@ -379,8 +378,6 @@ int lookup_paths_init(
 
                 strv_uniq(p->sysvinit_path);
                 strv_uniq(p->sysvrcnd_path);
-                path_strv_remove_empty(p->sysvinit_path);
-                path_strv_remove_empty(p->sysvrcnd_path);
 
                 if (!strv_isempty(p->sysvinit_path)) {
 

src/shared/path-util.c

@@ -190,13 +190,17 @@ char **path_strv_canonicalize(char **l) {
 
                 errno = 0;
                 u = canonicalize_file_name(t);
-                free(t);
 
                 if (!u) {
-                        if (errno == ENOMEM || !errno)
-                                enomem = true;
+                        if (errno == ENOENT)
+                                u = t;
+                        else {
+                                free(t);
+                                if (errno == ENOMEM || !errno)
+                                        enomem = true;
 
-                        continue;
+                                continue;
+                        }
                 }
 
                 l[k++] = u;