install with piped input fails if target file exists

Reproduction steps

$ echo foo | install /dev/stdin bar
$ echo foo | install /dev/stdin bar
install: No such file or directory

Expected behaviour

Piped content is written to target file as per coreutils behaviour, regardless of whether target file exists.

Actual behaviour

Error message printed about missing file only if target file already exists.

From an strace it looks like it trips up chasing symlinks for the stdin pipe:

readlink("/proc", 0x7ffe5f48f540, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/self", "328710", 1023)  = 6
readlink("/proc/328710", 0x7ffe5f48f540, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/328710/fd", 0x7ffe5f48f540, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/328710/fd/0", "pipe:[2063159]", 1023) = 14
readlink("/proc/328710/fd/pipe:[2063159]", 0x7ffe5f48f540, 1023) = -1 ENOENT (No such file or directory)

Start by reproducing the two install /dev/stdin bar commands from the issue and trace the install command's handling of piped stdin when bar already exists. Compare the behavior with the first run and GNU coreutils, then verify that piped content is written to the existing target without the missing-file error.