`tt rocks install` doesn't find Lua headers if there's `bin/tarantool`

[locker]

Bug description

I have ~/bin/tarantool on my laptop. I noticed that tt rocks install fails to find Lua headers if I run it from the home directory while it works fine if I run it from any other directory (I have Lua headers installed into /usr/local/include/tarantool). This is confusing and inconvenient.

Version

Tarantool CLI version 2.9.1, linux/amd64. commit: 22f0ba4 (v2.9.1-2-g22f0ba4f5148)

Steps to reproduce

1. Create bin directory in the home directory and copy the Tarantool binary to it:

   cd
   mkdir bin
   cp `which tarantool` bin

2. Add ~bin to PATH:

   export PATH=$HOME/bin:$PATH

3. Try to install a rock:

   tt rocks install checks

I get the following error:

Warning: failed to load command module luarocks.cmd.config: <string>:11: module luarocks.vendor.dkjson not found:
        no field package.preload['luarocks.vendor.dkjson']
        stat ./luarocks/vendor/dkjson.lua: no such file or directory
        stat /usr/local/share/lua/5.1/luarocks/vendor/dkjson.lua: no such file or directory
        stat /usr/local/share/lua/5.1/luarocks/vendor/dkjson/init.lua: no such file or directory,
Installing http://rocks.tarantool.org/checks-scm-1.rockspec
Cloning into 'checks'...
remote: Enumerating objects: 554, done.
remote: Counting objects: 100% (87/87), done.
remote: Compressing objects: 100% (50/50), done.
remote: Total 554 (delta 46), reused 37 (delta 37), pack-reused 467 (from 2)
Receiving objects: 100% (554/554), 131.24 KiB | 1.25 MiB/s, done.
Resolving deltas: 100% (277/277), done.

checks scm-1 depends on lua >= 5.1 (5.1-1 provided by VM: success)

Error: Failed finding Lua header files (searched at /home/vlad/include/include/tarantool). You may need to install them or configure LUA_INCDIR.