Load and test branches from another person's repository

gistfile1.r

# ====== Do this once =======
# Add the remote git repository (this needs to be done once):
git remote add wch https://github.com/wch/ggplot2.git
git fetch wch

# Install devtools (this needs to be done once):
install.packages("devtools")


# ====== Do this each time you want to try the code =======
# Check out the desired branch:
git checkout wch/feature/wdotplot
# It'll say something about detached HEAD state. This is OK.

# Load the library in R, without installing:
library(devtools)
load_all("/path/to/ggplot2/")
[test things out]


# ====== Other misc stuff =======
# To get your git repository back to the main branch:
git checkout master

# To get new changes from the repository:
git fetch wch

# You can remove the remote repository from your list by doing
git remote rm wch