Fix backport of redirect URL fix to 3.5

[m-burst]

Fix issues after #3614 (backport of #3613 to 3.5).

_HTTPMove.location is again the location parameter unchanged, no longer unconditionally converted to URL (which broke a test and might be seen as breaking by the users).

[webknjaz]

Thanks! Let's merge this once CI is green.

[m-burst]

@webknjaz It looks like the CI config on 3.5 branch does not pin pip version to <19.0 so the builds fail :(

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (3.5@74e3d74). Click here to learn what that means.
The diff coverage is 100%.

@@          Coverage Diff           @@
##             3.5    #3615   +/-   ##
======================================
  Coverage       ?   97.92%           
======================================
  Files          ?       44           
  Lines          ?     8566           
  Branches       ?     1382           
======================================
  Hits           ?     8388           
  Misses         ?       72           
  Partials       ?      106

Impacted Files	Coverage Δ
aiohttp/web_exceptions.py	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 74e3d74...7665f8c. Read the comment docs.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (3.5@74e3d74). Click here to learn what that means.
The diff coverage is 100%.

@@          Coverage Diff           @@
##             3.5    #3615   +/-   ##
======================================
  Coverage       ?   97.92%           
======================================
  Files          ?       44           
  Lines          ?     8566           
  Branches       ?     1382           
======================================
  Hits           ?     8388           
  Misses         ?       72           
  Partials       ?      106

Impacted Files	Coverage Δ
aiohttp/web_exceptions.py	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 74e3d74...7665f8c. Read the comment docs.

[webknjaz]

@m-burst you shouldn't pin pip. The bug related to it is tracked @ #3581. Please do not mix-in unrelated changes in PRs.

[m-burst]

@webknjaz OK, removed the commit pinning pip.
CI was green with it though, which means that the code changes are probably good to merge.