Python Installation script cannot detect existing rust installation on WSL

[ghost]

Issue Prelude

No Prelude
Please complete these steps and check these boxes (by putting an x inside
the brackets) before filing your issue:

• [ x] I have read and understood YCM's CONTRIBUTING document.
• [x ] I have read and understood YCM's CODE_OF_CONDUCT document.
• [ x] I have read and understood YCM's README, especially the
  Frequently Asked Questions section.
• [ x] I have searched YCM's issue tracker to find issues similar to the one I'm
  about to report and couldn't find an answer to my problem. (Example Google
  search.)
• [x ] If filing a bug report, I have included the output of vim --version.
• [x ] If filing a bug report, I have included the output of :YcmDebugInfo.
• [x ] If filing a bug report, I have attached the contents of the logfiles using
  the :YcmToggleLogs command.
• [ x] If filing a bug report, I have included which OS (including specific OS
  version) I am using.
• [ x] If filing a bug report, I have included a minimal test case that reproduces
  my issue, including what I expected to happen and what actually happened.
• [x ] If filing a installation failure report, I have included the entire output
  of install.py (or cmake/make/ninja) including its invocation
• [x ] I understand this is an open-source project staffed by volunteers and
  that any help I receive is a selfless, heartfelt gift of their free time. I
  know I am not entitled to anything and will be polite and courteous.
• [x ] I understand my issue may be closed if it becomes obvious I didn't
  actually perform all of these steps.

Thank you for adhering to this process! It ensures your issue is resolved
quickly and that neither your nor our time is needlessly wasted.

Issue Details

Provide a clear description of the problem, including the following key
questions: The python installation script cannot detect my rust installation while cargo and rustup both in PATH

• What did you do?
  simply run the script with python3 install.py --clang-completer --rust-completer

Include steps to reproduce here.
run script with python3 install.py --clang-completer --rust-completer
Include description of a minimal test case, including any actual code required
to reproduce the issue.

• What did you expect to happen?

Include description of the expected behaviour.

• What actually happened?
  I have rust installed, and .cargo/bin is in PATH, but the script cannot detect it, and install a new rust for me, that is not expected

Include description of the observed behaviour, including actual output,
screenshots, etc.

Diagnostic data

Output of vim --version

Place the output here, or a link to a gist.

Output of YcmDebugInfo

Place the output here, or a link to a gist.

Contents of YCM, ycmd and completion engine logfiles

Add let g:ycm_log_level = 'debug' to vimrc, restart Vim, reproduce the
issue, and include link here to a gist containing the entire logfiles for
ycm, ycmd and any completer logfiles listed by :YcmToggleLogs.

OS version, distribution, etc.

Include system information here.

Output of build/install commands

Include link to a gist containing the invocation and entire output of
install.py if reporting an installation issue.

[bstaletic]

The script is not meant to detect the rust toolchain in your $PATH. It installs the toolchain locally somewhere in YCM's directory, so it doesn't pollute your $HOME. This is not a bug.

Also read ycm-core/ycmd#1289