Build/package time requirement on git is burdensome

[colemickens]

It's not common for projects to invoke git during the course of a regular build. Further, Nix builds are sandboxed and can't access the network.

Can it be optional? The nix source stage can be instructed to fetch submodules, so the steps that it needs git for don't need to be executed anyway.

(Context: I'm packaging this for nixpkgs-wayland.)

[colemickens]

these derivations will be built:
  /nix/store/cjh0qill2swpalfj0x4w83wdsglv518q-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2.drv
building '/nix/store/cjh0qill2swpalfj0x4w83wdsglv518q-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2.drv'...
unpacking sources
unpacking source archive /nix/store/qlwf2v9k5g4xmzbvrnp2kjpmvrryllq6-source
source root is source
patching sources
configuring
meson flags: --buildtype=plain         --libdir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/lib --libexecdir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/libexec         --bindir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/bin --sbindir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/sbin         --includedir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/include         --mandir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/share/man --infodir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/share/info         --localedir=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2/share/locale         -Dauto_features=enabled         -Dwrap_mode=nodownload         --prefix=/nix/store/z9sy95v1w81kisgr6cxaza4mzd7zpaah-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2
The Meson build system
Version: 0.52.1
Source dir: /build/source
Build dir: /build/source/build
Build type: native build
Project name: wl-gammactl
Project version: undefined
C compiler for the host machine: /nix/store/9i8a5iq1kx2adjklqzf9xwrrsnqqnapf-gcc-wrapper-9.2.0/bin/cc (gcc 9.2.0 "gcc (GCC) 9.2.0")
C linker for the host machine: GNU ld.bfd 2.31.1
Host machine cpu family: x86_64
Host machine cpu: x86_64
Found pkg-config: /nix/store/50vxsm7w48l5mqa2f114c43vcyyixxn0-pkg-config-0.29.2/bin/pkg-config (0.29.2)
Run-time dependency gtk+-3.0 found: YES 3.24.13
Run-time dependency wlroots found: YES 0.10.0
Run-time dependency wayland-client found: YES 1.17.0
Program glib-compile-resources found: YES (/nix/store/2l3lj1v8skfy6z86nvdac5anh6j1ppz2-glib-2.62.4-dev/bin/glib-compile-resources)
Program git found: NO

meson.build:32:0: ERROR: Program(s) ['git'] not found or not executable

A full log can be found at /build/source/build/meson-logs/meson-log.txt
builder for '/nix/store/cjh0qill2swpalfj0x4w83wdsglv518q-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2.drv' failed with exit code 1
error: build of '/nix/store/cjh0qill2swpalfj0x4w83wdsglv518q-wl-gammactl-611846ce8f5f6e7fe1afb100416cceb8af54afb2.drv' failed