Incorrect group-by columns when joining grouped data frames with overlapping columns

[davidkretch]

join updates overlapping column names, but does not update corresponding group column names in attribute vars. This becomes an issue when a group column is not used in the join. The resulting data frame causes errors in mutate.

library(dplyr)


df1 <- data.frame(x = 1:10, y = 1:10)
df2 <- df1

df1g <- df1 %>% group_by(x, y)

df3 <- inner_join(df1g, df2, by = "x")

df3 %>%
  mutate(a = 1)

Output:

Error in mutate_impl(.data, dots) : unknown column 'y.x' 

I have a fix and will submit a pull request.