DESTDIR not fully implemented

[dmacks]

Building v2021 on OS X 10.13:

./configure --prefix=/sw --with-texpath=/sw/etc/texmf.local/tex/latex/html 
make
make install DESTDIR=/sw/build.build/root-latex2html-2021-1

/sw is my ultimate runtime prefix, but /sw/build.build/root-latex2html-2021-1 is a staging directory that later gets copied to the live / filesystem. During make install:

Info: Installed /sw/build.build/root-latex2html-2021-1/sw/share/lib/latex2html/styles/norsk.perl
Info: Installed /sw/build.build/root-latex2html-2021-1/sw/share/lib/latex2html/styles/nynError: Could not create directory "/sw/etc/texmf.local/tex": Permission denied

Error: Cannot install LaTeX2HTML style files in /sw/etc/texmf.local/tex/latex/html
orsk.perl
Info: Installed /sw/build.build/root-latex2html-2021-1/sw/share/lib/latex2html/styles/polish.perl

and

Info: Installed /sw/build.build/root-latex2html-2021-1/sw/share/lib/latex2html/versions/utf8ru.pl

Note: trying to install LaTeX2HTML style files in TeX directory tree
     (/sw/etc/texmf.local/tex/latex/html)

In the "Info:" messages, I see that files are getting placed in the staging directory. However, the "Error:" and "Note:" indicate that some other actions are not respecting the DESTDIR and instead are trying (and obviously failing) to write to the live system on my build box.