Build failed on Arch Linux

[Pryx]

servo/servo#4032 When trying to build servo, build fails at this script. As @SimonSapin mentioned, problem is with Python version. The script assumes version 2.x, whereas on Arch Linux it is 3.x.

Build failed, waiting for other jobs to finish...
Failed to run custom build command for `rustuv v0.0.1 (https://github.com/servo/green-rs?ref=servo#9300d7e7)`
Process didn't exit successfully: `make -C build` (status=2)
--- stdout
make: Entering directory '/home/pryx/.cargo/git/checkouts/green-rs-b9cfdf70c4e4296e/servo/librustuv/build'
(cd libuv && python ./gyp_uv.py -f make -Dtarget_arch=x64 \
   -D ninja \
   -DOS=linux \
   -Goutput_dir=/home/pryx/servo/target/native/rustuv-31b2f01c9f5360db/libuv  --generator-output /home/pryx/servo/target/native/rustuv-31b2f01c9f5360db/libuv)
Makefile:50: recipe for target '/home/pryx/servo/target/native/rustuv-31b2f01c9f5360db/libuv/Makefile' failed
make: Leaving directory '/home/pryx/.cargo/git/checkouts/green-rs-b9cfdf70c4e4296e/servo/librustuv/build'

--- stderr
  File "./gyp_uv.py", line 51
    print 'Error running GYP'
                            ^
SyntaxError: Missing parentheses in call to 'print'
make: *** [/home/pryx/servo/target/native/rustuv-31b2f01c9f5360db/libuv/Makefile] Error 1

[SimonSapin]

In librustuv/build/Makefile, replace the two instances of python ./gyp_uv.py with $(PYTHON) ./gyp_uv.py, add add near the top of the file something like PYTHON = $(shell which python2.7 > /dev/null && echo python2.7 || echo python) (untested.)