Installing a new kernel from a kernel build tree with "make install" generates this warning:

  grep: warning: stray \ before /

After some digging, I found that it comes from this line in /usr/bin/kdumpctl:

 _grubby_kernel_str=$(grubby --info ALL | grep -E "^kernel=.*$_release(\/\w+)?\"$")

where grep is warning that it should perhaps be (removing \ before /):

 _grubby_kernel_str=$(grubby --info ALL | grep -E "^kernel=.*$_release(/\w+)?\"$")

That does eliminates the warning.

Reproducible: Always

Steps to Reproduce:
1. Build kernel from source tree
2. make install
3.
Actual Results:  
Generates a warning, but the install works as expected (modulo some other fixed packages).

Expected Results:  
No warnings.