version.py fails when using git worktrees
When a specific release of gstreamer is checked out via git worktrees, there is no .git subdirectory in the /subprojects/x264 directory. Instead, there is a .git file which contains the path to the actual gitdir. This causes the is_git variable in version.py line 52 to be False. As a consequence version.py returns exit status 255, which breaks the process of configuring the x264 gstremaer subproject with meson.