3.7.7 breakes the build on Windows

[henrify]

Cloning the repo and trying to build fails at the 'browserify' script on Windows 8.1 with Node 4.4.3 64bit.

3.7.3 builds fine in windows.

Below is output from running just the browserify script.

---

PS F:\Projects_Modified\JavaScript\when-fix> npm run browserify

when@3.7.7 browserify F:\Projects_Modified\JavaScript\when-fix
npm run browserify-es6 && npm run browserify-when && npm run browserify-debug

when@3.7.7 browserify-es6 F:\Projects_Modified\JavaScript\when-fix
browserify -s Promise es6-shim/Promise.browserify-es6.js --no-detect-globals --debug | exorcist -b . -r https://raw.githubusercontent.com/cujojs/when/`git rev-parse HEAD` es6-shim/Promise.js.map >es6-shim/Promise.js

when@3.7.7 browserify-when F:\Projects_Modified\JavaScript\when-fix
mkdir -p dist/browser && browserify -s when build/when.browserify.js --no-detect-globals --debug | exorcist -b . -r https://raw.githubusercontent.com/cujojs/when/`git rev-parse HEAD` dist/browser/when.js.map >dist/browser/when.js

The syntax of the command is incorrect.

npm ERR! Windows_NT 6.3.9600
npm ERR! argv "C:\Program Files\nodejs\node.exe" "C:\Program Files\nodejs\node_modules\npm\bin\npm-cli.js" "run" "browserify-when"
npm ERR! node v4.4.3
npm ERR! npm v2.15.1
npm ERR! code ELIFECYCLE
npm ERR! when@3.7.7 browserify-when: mkdir -p dist/browser && browserify -s when build/when.browserify.js --no-detect-globals --debug | exorcist -b . -r https://raw.githubusercontent.com/cujojs/when/git rev-parse HEADdist/browser/when.js.map >d ist/browser/when.js
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the when@3.7.7 browserify-when script 'mkdir -p dist/browser && browserify -s when build/when.browserify.js --no-detect-globals --debug | exorcist -b . -r https://raw.githubusercontent.com/cujojs/when/`git rev-parse HEADdist/br owser/when.js.map >dist/browser/when.js'. npm ERR! This is most likely a problem with the when package, npm ERR! not with npm itself. npm ERR! Tell the author that this fails on your system: npm ERR! mkdir -p dist/browser && browserify -s when build/when.browserify.js --no-detect-globals --debug | exorcist -b . -r https://raw.githubusercontent.com/cujojs/when/git rev-parse HEAD` dist/browser/when.js.map >dist/browser/when.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs when
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!
npm ERR! npm owner ls when
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR! F:\Projects_Modified\JavaScript\when-fix\npm-debug.log

npm ERR! Windows_NT 6.3.9600
npm ERR! argv "C:\Program Files\nodejs\node.exe" "C:\Program Files\nodejs\node_modules\npm\bin\npm-cli.js" "run" "browserify"
npm ERR! node v4.4.3
npm ERR! npm v2.15.1
npm ERR! code ELIFECYCLE
npm ERR! when@3.7.7 browserify: npm run browserify-es6 && npm run browserify-when && npm run browserify-debug
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the when@3.7.7 browserify script 'npm run browserify-es6 && npm run browserify-when && npm run browserify-debug'.
npm ERR! This is most likely a problem with the when package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! npm run browserify-es6 && npm run browserify-when && npm run browserify-debug
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs when
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!
npm ERR! npm owner ls when
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR! F:\Projects_Modified\JavaScript\when-fix\npm-debug.log

[henrify]

Checking more. Are you trying to use unix backticks? as in git rev-parse HEAD?

[briancavalier]

We can switch this to use $() like you suggested. I should have time to do that tonight or tomorrow.