[BUG] `make install' partly ignores `NO_INSTALL_HARDLINKS'

[Alexander Ost <ost@ieee.org>]

Hello,

I tried to install git on a filesystem that does not support hard
links (specifically, on a Linux bind mount).

Despite installing with `make NO_INSTALL_HARDLINKS=1 install', the
installation process tries to create hard links, and the installation
fails (a quick workaround is `sed -i git-gui/Makefile -e "s/ln /ln -s
/g"').

Here's the bugreport:

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Thank you for filling out a Git bug report!
Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)
./configure --prefix=/filesystem_without_hardlink_support
make
make NO_INSTALL_HARDLINKS=1 install

What did you expect to happen? (Expected behavior)
Successful installation.

What happened instead? (Actual behavior)
Installation fails with error
  ln: failed to create hard link
‘/filesystem_without_hardlink_support/libexec/git-core/git-citool’ =>
‘/filesystem_without_hardlink_support/libexec/git-core/git-gui’:
Operation not permitted

What's different between what you expected and what actually happened?
The makefile `git-gui/Makefile' tries to create hard links. This is
not expected when running `make NO_INSTALL_HARDLINKS=1 install'

Anything else you want to add:

Please review the rest of the bug report below.
You can delete any lines you don't wish to share.

[System Info]
git version:
git version 2.27.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
uname: Linux 3.10.0-957.10.1.el7.x86_64 #1 SMP Mon Mar 18 15:06:45 UTC
2019 x86_64
compiler info: gnuc: 4.8
libc info: glibc: 2.17


[Enabled Hooks]
not run from a git repository - no hooks to show
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Thanks for checking this!

Best,
/alex