add test for util_path_isrelated dav-2 tip

port tests to UCX4 dav-2

update ucx to version 4.0 dav-2

remove unnecessary usage of cx_hash_key_str dav-2

replace a bunch of cxBufferWrite calls with cxBufferPutString dav-2

update ucx dav-2

update uwproj dav-2

update ucx dav-2

update ucx default

add TODOs for using modern ucx features dav-2

(0) -300 -100 -10 tip

mercurial