Fix the following build failure:
```
config.status: executing libtool commands
building
make flags: SHELL=/nix/store/548wfw1i43glkx8lkyjmbg59h6127qky-bash-4.3-p39/bin/bash
./scripts/MakeHeader.py ColumnsPanel.c
/usr/bin/env: python: No such file or directory
Makefile:2164: recipe for target 'ColumnsPanel.h' failed
make: *** [ColumnsPanel.h] Error 127
builder for ‘/nix/store/6rai1vs6jsw8y5z5jff98f0f8jzfa12n-htop-1.0.3-584-8f07868f.drv’ failed with exit code 2
```
```
william@exodus ~> htop
htop 1.0.3 aborting. Please report bug at http://hisham.hm/htop
Please include in your report the following backtrace:
htop(CRT_handleSIGSEGV+0x32)[0x4177b2]
/nix/store/xaz2f0mxklh0kh231h6spzbiblq1fm5b-glibc-2.21/lib/libc.so.6(+0x33460)[0x7f9fb9157460]
/nix/store/bdnzh93qibc3cimdw8fj94wwa4wjpw5f-ncurses-6.0/lib/libncursesw.so.6(+0x33f91)[0x7f9fb97faf91]
/nix/store/bdnzh93qibc3cimdw8fj94wwa4wjpw5f-ncurses-6.0/lib/libncursesw.so.6(doupdate_sp+0xc1d)[0x7f9fb97fe0ad]
/nix/store/bdnzh93qibc3cimdw8fj94wwa4wjpw5f-ncurses-6.0/lib/libncursesw.so.6(wrefresh+0x39)[0x7f9fb97ecf09]
/nix/store/bdnzh93qibc3cimdw8fj94wwa4wjpw5f-ncurses-6.0/lib/libncursesw.so.6(_nc_wgetch+0x12a)[0x7f9fb97e583a]
/nix/store/bdnzh93qibc3cimdw8fj94wwa4wjpw5f-ncurses-6.0/lib/libncursesw.so.6(wgetch+0x25)[0x7f9fb97e6555]
htop(ScreenManager_run+0x15a)[0x40ee8a]
htop(main+0x487)[0x4069b7]
/nix/store/xaz2f0mxklh0kh231h6spzbiblq1fm5b-glibc-2.21/lib/libc.so.6(__libc_start_main+0xf5)[0x7f9fb9144995]
htop(_start+0x29)[0x406af9]
Additionally, in order to make the above backtrace useful,
please also run the following command to generate a disassembly of your
binary:
objdump -d `which htop` > ~/htop.objdump
and then attach the file ~/htop.objdump to your bug report.
Thank you for helping to improve htop!
fish: “htop” terminated by signal SIGABRT (Abort)
```
