node_cache: Preserve symlinks when copying an old node_modules tree.
node_cache: Preserve symlinks when copying an old node_modules tree.

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulipchat.com>

punchagan/zulip,andersk/zulip,brainwane/zulip,brainwane/zulip,punchagan/zulip,brainwane/zulip,showell/zulip,timabbott/zulip,synicalsyntax/zulip,showell/zulip,andersk/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,shubhamdhama/zulip,hackerkid/zulip,zulip/zulip,synicalsyntax/zulip,punchagan/zulip,showell/zulip,brainwane/zulip,synicalsyntax/zulip,synicalsyntax/zulip,timabbott/zulip,kou/zulip,andersk/zulip,shubhamdhama/zulip,zulip/zulip,synicalsyntax/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,kou/zulip,rht/zulip,zulip/zulip,punchagan/zulip,brainwane/zulip,zulip/zulip,brainwane/zulip,shubhamdhama/zulip,rht/zulip,timabbott/zulip,rht/zulip,hackerkid/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,eeshangarg/zulip,timabbott/zulip,kou/zulip,kou/zulip,zulip/zulip,eeshangarg/zulip,shubhamdhama/zulip,synicalsyntax/zulip,rht/zulip,timabbott/zulip,shubhamdhama/zulip,punchagan/zulip,rht/zulip,andersk/zulip,shubhamdhama/zulip,synicalsyntax/zulip,eeshangarg/zulip,showell/zulip,rht/zulip,hackerkid/zulip,punchagan/zulip,showell/zulip,timabbott/zulip,hackerkid/zulip,showell/zulip,punchagan/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip,hackerkid/zulip,shubhamdhama/zulip,timabbott/zulip,kou/zulip,brainwane/zulip,kou/zulip