too many diffs when revdep can not be installed using one version

[tdhock]

for example revdep do

> (sig.diff.dt <- myDiff(Rvers))
Key: <checking>
                                                        checking master release
                                                          <char> <char>  <char>
 1:                                            'build' directory   <NA>      OK
 2:                                 DESCRIPTION meta-information   <NA>      OK
 3:                                        PDF version of manual   <NA>      OK
 4:                                 R code for possible problems   <NA>      OK
 5:                             R files for non-ASCII characters   <NA>      OK
 6:                                    R files for syntax errors   <NA>      OK
 7:                                          Rd \\usage sections   <NA>      OK
 8:                                                  Rd contents   <NA>      OK
 9:                                          Rd cross-references   <NA>      OK
10:                                                     Rd files   <NA>      OK
11:                                                  Rd metadata   <NA>      OK
12:                                S3 generic/method consistency   <NA>      OK
13:                                       dependencies in R code   <NA>      OK
14:                                                     examples   <NA>      OK
15:                                         files in 'vignettes'   <NA>      OK
16:                            for code/documentation mismatches   <NA>      OK
17:                                          for left-over files   <NA>      OK
18:                            for missing documentation entries   <NA>      OK
19:                        for unstated dependencies in examples   <NA>      OK
20:                       for unstated dependencies in vignettes   <NA>      OK
21:                                       foreign function calls   <NA>      OK
22:                                            index information   <NA>      OK
23:                              installed files from 'inst/doc'   <NA>      OK
24:             loading without being on the library search path   <NA>      OK
25:                                            package directory   <NA>      OK
26:                                       package subdirectories   <NA>      OK
27:                                            package vignettes   <NA>      OK
28:                              re-building of vignette outputs   <NA>      OK
29:                                        replacement functions   <NA>      OK
30:                                              top-level files   <NA>      OK
31:                        whether package 'do' can be installed  ERROR      OK
32: whether the namespace can be loaded with stated dependencies   <NA>      OK
33:                whether the namespace can be unloaded cleanly   <NA>      OK
34:                            whether the package can be loaded   <NA>      OK
35:   whether the package can be loaded with stated dependencies   <NA>      OK
36:                  whether the package can be unloaded cleanly   <NA>      OK
                                                        checking master release

[tdhock]

* using log directory '/tmp/th798/9494771/R-devel/310/do.Rcheck'
* using R Under development (unstable) (2024-04-03 r86327)
* using platform: x86_64-pc-linux-gnu
* R was compiled by
    gcc (Spack GCC) 12.2.0
    GNU Fortran (Spack GCC) 12.2.0
* running under: Red Hat Enterprise Linux 8.9 (Ootpa)
* using session charset: ASCII
* checking for file 'do/DESCRIPTION' ... OK
* checking extension type ... Package
* this is package 'do' version '2.0.0.0'
* package encoding: UTF-8
* checking package namespace information ... OK
* checking package dependencies ... OK
* checking if this is a source package ... OK
* checking if there is a namespace ... OK
* checking for executable files ... OK
* checking for hidden files and directories ... OK
* checking for portable file names ... OK
* checking for sufficient/correct file permissions ... OK
* checking whether package 'do' can be installed ... ERROR
Installation failed.
See '/tmp/th798/9494771/R-devel/310/do.Rcheck/00install.out' for details.
* DONE

[tdhock]

https://github.com/Rdatatable/data.table/issues/6000