Hmm the uboot.txt file got corrupted somehow, here is another try:
fallen@fallen-ThinkPad-X260:~/dev/snappy/paros/snappy_image/u-boot/tools$ ./mkenvimage -r -s 131072 -o uboot.env uboot.txt
fallen@fallen-ThinkPad-X260:~/dev/snappy/paros/snappy_image/u-boot/tools$ uboot-go uboot.env print
panic: invalid line "${prefix}${script}; source ${scriptaddr}" (corrupted file?)

goroutine 1 [running]:
panic(0x4d7280, 0xc8200742e0)
	/usr/lib/go-1.6/src/runtime/panic.go:464 +0x3e6
github.com/mvo5/uboot-go/uenv.parseData(0xc8200da005, 0x93f, 0x3fdfb, 0xc82003fb6a)
	/home/fallen/gocode/src/github.com/mvo5/uboot-go/uenv/env.go:97 +0x38e
github.com/mvo5/uboot-go/uenv.Open(0x7fff77a2336f, 0x9, 0x0, 0x0, 0x0)
	/home/fallen/gocode/src/github.com/mvo5/uboot-go/uenv/env.go:82 +0x4a8
main.main()
	/home/fallen/gocode/src/github.com/mvo5/uboot-go/main.go:19 +0x605

fallen@fallen-ThinkPad-X260:~/dev/snappy/paros/snappy_image/u-boot/tools$ cat uboot.txt


arch=arm
baudrate=115200
board=paros
board_name=paros
boot_a_script=load ${devtype} ${devnum}:${bootpart} ${scriptaddr}
${prefix}${script}; source ${scriptaddr}
boot_extlinux=sysboot ${devtype} ${devnum}:${bootpart} any ${scriptaddr}
${prefix}extlinux/extlinux.conf
boot_net_usb_start=usb start
boot_prefixes=/ /boot/
boot_script_dhcp=boot.scr.uimg
boot_scripts=boot.scr.uimg boot.scr
boot_targets=mmc1 mmc0 usb0 pxe dhcp
bootcmd=run distro_bootcmd
bootcmd_dhcp=run boot_net_usb_start; if dhcp ${scriptaddr}
${boot_script_dhcp}; then source ${scriptaddr}; fi
bootcmd_mmc0=setenv devnum 0; run mmc_boot
bootcmd_mmc1=setenv devnum 1; run mmc_boot
bootcmd_pxe=run boot_net_usb_start; dhcp; if pxe get; then pxe boot; fi
bootcmd_usb0=setenv devnum 0; run usb_boot
bootdelay=2
bootfstype=ext4
cpu=armv8
devnum=0
devplist=1
devtype=mmc
dfu_alt_info=kernel ram 0x80080000;dtb ram 0x83000000;initramfs ram
0x84000000
dfu_boot=dfu 0 ram 0; booti 0x80080000 - 0x83000000
distro_bootcmd=for target in ${boot_targets}; do run bootcmd_${target}; done
fdt_addr_r=0x82000000
fdt_copy_node_names=/memory-controller@7001b000
fdt_copy_src_addr=0x83080000
fdt_high=ffffffffffffffff
initrd_high=ffffffffffffffff
kernel_addr_r=0x80080000
loadaddr=0x80080000
lp0_vec=0x1000@0xff2bf000
mmc_boot=if mmc dev ${devnum}; then setenv devtype mmc; run
scan_dev_for_boot_part; fi
nvdumper_reserved=0xff23f000
pxefile_addr_r=0x90100000
ramdisk_addr_r=0x83100000
revision=hw00
scan_dev_for_boot=echo Scanning ${devtype} ${devnum}:${bootpart}...; for
prefix in ${boot_prefixes}; do run scan_dev_for_extlinux; run
scan_dev_for_scripts; done
scan_dev_for_boot_part=part list ${devtype} ${devnum} -bootable
devplist; env exists devplist || setenv devplist 1; for bootpart in
${devplist}; do if fstype ${devtype} ${devnum}:${bootparte
scan_dev_for_extlinux=if test -e ${devtype} ${devnum}:${bootpart}
${prefix}extlinux/extlinux.conf; then echo Found
${prefix}extlinux/extlinux.conf; run boot_extlinux; echo SCRIPT FAILED: coi
scan_dev_for_scripts=for script in ${boot_scripts}; do if test -e
${devtype} ${devnum}:${bootpart} ${prefix}${script}; then echo Found
U-Boot script ${prefix}${script}; run boot_a_script; ee
scriptaddr=0x90000000
soc=tegra210
stderr=serial
stdin=serial
stdout=serial
usb_boot=usb start; if usb dev ${devnum}; then setenv devtype usb; run
scan_dev_for_boot_part; fi
vendor=parrot