correct bug

1 job for master in 17 minutes and 28 seconds (queued for 1 second)
Name Stage Failure
pages Deploy
/usr/local/bin/pandoc +RTS -K512m -RTS --to html4 --from markdown+autolink_bare_uris+tex_math_single_backslash --output agrodatascience.html --lua-filter /usr/local/lib/R/site-library/bookdown/rmarkdown/lua/custom-environment.lua --lua-filter /usr/local/lib/R/site-library/rmarkdown/rmarkdown/lua/pagebreak.lua --lua-filter /usr/local/lib/R/site-library/rmarkdown/rmarkdown/lua/latex-div.lua --metadata-file /tmp/Rtmpj2sWVR/file4e1837956321 --wrap preserve --standalone --section-divs --table-of-contents --toc-depth 3 --template /usr/local/lib/R/site-library/bookdown/templates/gitbook.html --highlight-style pygments --number-sections --include-in-header /tmp/Rtmpj2sWVR/rmarkdown-str4e185a892669.html --mathjax --citeproc 
Error in get(name, envir = asNamespace(pkg), inherits = FALSE) :
object 'is_abs_path' not found
Calls: local ... <Anonymous> -> <Anonymous> -> move_files_html -> ::: -> get
In addition: There were 29 warnings (use warnings() to see them)
Execution halted
Error: Failed to run 'render_book' in a new R session.
Execution halted
Cleaning up file based variables
ERROR: Job failed: exit code 1