Install python pacakge from `.whl` file

[Hamzeh Nasajpour]

Hi,

I have to package a python library via `whl` file, is it feasible? 
I took a look in the guix packages, and found something in `tensorflow` package 
to installing from `whl` file,
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/machine-learning.scm#n1784

but I get these errors when I want to install my package. I'm using the 
following lines in my package definition too:
```
...
                     (invoke "python3" "-m" "pip" "install" source
                       (string-append "--prefix=" %output))
...
```

Error:
```
WARNING: The directory '/homeless-shelter/.cache/pip/http' or its parent 
directory is not owned by the current user and the cache has been disabled. 
Please check the permissions and owner of that directory. If executing pip with 
sudo, you may want sudo's -H flag.
WARNING: The directory '/homeless-shelter/.cache/pip' or its parent directory 
is not owned by the current user and caching wheels has been disabled. check 
the permissions and owner of that directory. If executing pip with sudo, you 
may want sudo's -H flag.
Processing 
/gnu/store/pbv52yan4xnwbi426qywcfkls681k3lg-etebase-0.31.2-cp38-cp38-manylinux2010_x86_64.whl
Collecting msgpack>=1.0.0 (from pbv52yan4xnwbi426qywcfkls681k3lg==etebase)
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, 
status=None)) after connection broken by 
'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection 
object at 0x7ffff6c443a0>: Failed to establish a new connection: [Errno -2] 
Name or service not known')': /simple/msgpack/
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, 
status=None)) after connection broken by 
'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection 
object at 0x7ffff6c445b0>: Failed to establish a new connection: [Errno -2] 
Name or service not known')': /simple/msgpack/
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, 
status=None)) after connection broken by 
'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection 
object at 0x7ffff6c44280>: Failed to establish a new connection: [Errno -2] 
Name or service not known')': /simple/msgpack/
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, 
status=None)) after connection broken by 
'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection 
object at 0x7ffff6c30280>: Failed to establish a new connection: [Errno -2] 
Name or service not known')': /simple/msgpack/
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, 
status=None)) after connection broken by 
'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection 
object at 0x7ffff6c30580>: Failed to establish a new connection: [Errno -2] 
Name or service not known')': /simple/msgpack/
  ERROR: Could not find a version that satisfies the requirement msgpack>=1.0.0 
(from pbv52yan4xnwbi426qywcfkls681k3lg==etebase) (from versions: none)
ERROR: No matching distribution found for msgpack>=1.0.0 (from 
pbv52yan4xnwbi426qywcfkls681k3lg==etebase)
Backtrace:
           3 (primitive-load "/gnu/store/0ab4p5n88lzdlgq6jwb5qi9nw52?")
In ice-9/eval.scm:
   191:35  2 (_ #f)
    619:8  1 (_ #(#(#(#(#(#(#(#<directory (guil?> ?) ?) ?) ?) ?) ?) ?))
In guix/build/utils.scm:
    654:6  0 (invoke _ . _)

guix/build/utils.scm:654:6: In procedure invoke:
ERROR:
  1. &invoke-error:
      program: "python3"
      arguments: ("-m" "pip" "install" 
"/gnu/store/pbv52yan4xnwbi426qywcfkls681k3lg-etebase-0.31.2-cp38-cp38-manylinux2010_x86_64.whl"
 "--prefix=/gnu/store/18vg8h9yh2a3f6vlqn2kcxhbrfzrchns-python-etebase-0.31.2")
      exit-status: 1
      term-signal: #f
      stop-signal: #f
````
--

Hamzeh Nasajpour
PantherX Team