`rcs_diff` |yes |yes |yes |yes |no |yes |yes |yes
`rcs_getctime` |fast |slow |slow |slow |slow |slow |slow |slow
`rcs_getmtime` |fast |slow |slow |no |no |no |no |no
+`rcs_preprevert` |yes |no |no |no |no |no |no |no
+`rcs_revert` |yes |no |no |no |no |no |no |no
anonymous push |yes |no |no |no |no |no |no |no
conflict handling |yes |yes |yes |buggy |yes |yes |yes |yes
openid username |yes |no |no |no |no |no |no |no