Can't knit R markdown after updating RStudio to version 1.2



After updating RStudio from version 1.1 to 1.2, when I try to knit an R markdown document (even those freshly created from a template) I get this error message in "R Markdown" pane:

Error: unexpected end of input
Execution halted


It looks like this has been reported and confirmed as an issue (for Windows, at least):


Thanks for taking the time to test! We've fixed this in the latest daily builds of RStudio and hope to get the fix promoted to the preview release ASAP.