Error(s) in re-building vignettes:
  ...
--- re-building ‘CombiningDratAndTravis.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'CombiningDratAndTravis.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘CombiningDratAndTravis.pdf’ or ‘CombiningDratAndTravis.html’ for vignette with name ‘CombiningDratAndTravis’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘CombiningDratAndTravis.md’

--- re-building ‘DratFAQ.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'DratFAQ.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘DratFAQ.pdf’ or ‘DratFAQ.html’ for vignette with name ‘DratFAQ’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘DratFAQ.md’

--- re-building ‘DratForPackageAuthors.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'DratForPackageAuthors.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘DratForPackageAuthors.pdf’ or ‘DratForPackageAuthors.html’ for vignette with name ‘DratForPackageAuthors’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘DratForPackageAuthors.md’

--- re-building ‘DratForPackageUsers.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'DratForPackageUsers.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘DratForPackageUsers.pdf’ or ‘DratForPackageUsers.html’ for vignette with name ‘DratForPackageUsers’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘DratForPackageUsers.md’

--- re-building ‘DratStepByStep.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'DratStepByStep.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘DratStepByStep.pdf’ or ‘DratStepByStep.html’ for vignette with name ‘DratStepByStep’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘DratStepByStep.md’

--- re-building ‘WhyDrat.md’ using mdweave_to_html
Cannot find pandoc. Not able to weave vignette.
Error: processing vignette 'WhyDrat.md' failed with diagnostics:
Failed to locate ‘weave’ output file ‘WhyDrat.pdf’ or ‘WhyDrat.html’ for vignette with name ‘WhyDrat’ and engine ‘simplermarkdown::mdweave_to_html’. The following files exist in working directory ‘/home/ripley/R/packages/tests32/drat.Rcheck/vign_test/drat/vignettes’: ‘CombiningDratAndTravis.md’ (3570 bytes), ‘DratFAQ.md’ (7091 bytes), ‘DratForPackageAuthors.md’ (6514 bytes), ‘DratForPackageUsers.md’ (2796 bytes), ‘DratStepByStep.md’ (8217 bytes), ‘WhyDrat.md’ (4005 bytes), ‘water.css’ (1193 bytes)
--- failed re-building ‘WhyDrat.md’

SUMMARY: processing the following files failed:
  ‘CombiningDratAndTravis.md’ ‘DratFAQ.md’ ‘DratForPackageAuthors.md’
  ‘DratForPackageUsers.md’ ‘DratStepByStep.md’ ‘WhyDrat.md’

Error: Vignette re-building failed.
Execution halted