brew: Incorrect selection of Xcode location

After installing homebrew, it found an incorrect Xcode version and force me to update Xcode although it up-to-date.

Here is the case: I have one drive with installed OSX 10.9 and there is XCode 5.1 here

I’ve installed OS 10.12 on second drive and also installed latest XCode 8.1

After installing homebrew on second drive it asking me to update XCode.

$ brew doctor
Warning: Your Xcode (5.1) is too outdated.
Please update to Xcode 8.1 (or delete it).
Xcode can be updated from the App Store.

$ brew config
HOMEBREW_VERSION: 1.1.1
HOMEBREW_PREFIX: /usr/local
HOMEBREW_REPOSITORY: /usr/local/Homebrew
HOMEBREW_CELLAR: /usr/local/Cellar
HOMEBREW_BOTTLE_DOMAIN: https://homebrew.bintray.com
Homebrew Ruby: 2.0.0-p648
Clang: 8.0 build 800
Git: 2.9.3 => /Library/Developer/CommandLineTools/usr/bin/git
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
Java: N/A
macOS: 10.12.1-x86_64
Xcode: 5.1 => /Volumes/MAC X 9/Applications/Xcode.app/Contents/Developer
CLT: 8.1.0.0.1.1476494586
X11: N/A

I’ve tried to unmount the first drive and then homebrew found correct Xcode, but when I mount it back Homebrew switching to wrong Xcode version from first drive.